On Tue, 9 Oct 2001, Jerry Lake wrote:
> you are correct, that is what it was I guess I will have to learn a
> few more modules, so I don't do that
Glad to be of help. Don't worry; I've done something like that a few
times myself... *grin*
From alan.gauld@bt.com Wed Oct 10 10:22:40 2001
From: alan.gauld@bt.com (alan.gauld@bt.com)
Date: Wed, 10 Oct 2001 10:22:40 +0100
Subject: [Tutor] converting decimals to fractions
Message-ID: <5104D4DBC598D211B5FE0000F8FE7EB20E66BFCF@mbtlipnt02.btlabs.bt.co.uk>
Hi Blake,
Two points to make:
1) Your method will work.
2) Its not the most efficient way to use a dictionary.
Given (2), another approach which might(I haven't tested
this!) be more efficient is to extract the fractional part,
round to the required precision - looks like 6 digits then
do a binary chop search on a list of tuples. The
indexing/sequential access of the list might in this
case be better than searching the values of a dictionary.
(Wth 64 entries your *worst* case should be 6 tests...)
The tuples would of course contain the fraction string
and the equivalent number equivalent. As ever with floats
beware of rounding errors.
Just some thoughts.
Alan G.
From alan.gauld@bt.com Wed Oct 10 10:39:04 2001
From: alan.gauld@bt.com (alan.gauld@bt.com)
Date: Wed, 10 Oct 2001 10:39:04 +0100
Subject: [Tutor] running programs
Message-ID: <5104D4DBC598D211B5FE0000F8FE7EB20E66BFD0@mbtlipnt02.btlabs.bt.co.uk>
This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
------_=_NextPart_001_01C1516F.66A343C0
Content-Type: text/plain;
charset="iso-8859-1"
I am learning to program, I have chosen Python as my first language to
learn. My question is, I have written some command line programs (small
programs) and I would like to run them on a different computer.
Well done, thats the hardest bit over :-)
How can I do this without installing Python on the second computer?
There are a few packages around that can do this.
py2exe seems to be the favourite but Gordon McMillan
also has an installer program on the ActiveState
site somewhere.
However first to clear up some common misconceptions:
Basically how do you package programs to run on other computers as
"software" without actually installing Python to run them?
You can't. All the above solutions do is pack up the smallest bit of python
needed to run your program and combine it with your program as a single
unit.
This is true of every program even C++ ones.
If you delete the MFC DLL on your windows PC you will
find that virtually nothing works! Similarly on Unix
if you delete the libc files nothing will work. This
is because every program is built to use a standard
runtime environment, its just that some of these
environments are installed by default on the operating system while others -
like Python - must be installed later.
For instance, if I wrote a Python program with Tkinter how would that
program be packaged to be installed and run on a computer?
Thanks,
Chris Nally
Louisville, Kentucky
------_=_NextPart_001_01C1516F.66A343C0
Content-Type: text/html;
charset="iso-8859-1"
I am learning to program, I have chosen
Python as my first language to learn. My question is, I have written
some command line programs (small programs) and I would like to run them on a
different computer.
Well done, thats the hardest bit over
:-)
How can I do
this without installing Python on the second computer?
There are a few packages around that can do
this.
py2exe seems to be the favourite but Gordon McMillan
also has an installer program on the ActiveState
site somewhere.
However first to clear up some common
misconceptions:
Basically how do
you package programs to run on other computers as "software" without actually
installing Python to run them?
You can't. All the above solutions do is pack up the
smallest bit of python needed to run your program and combine it with your
program as a single unit.
This is true of every program even C++
ones.
If you delete the MFC DLL on your windows PC you will
find that virtually nothing works! Similarly on Unix
if you delete the libc files nothing will work. This
is because every program is built to use a standard
runtime environment, its just that some of these
environments are installed by default on the operating
system while others - like Python - must be installed later.
For instance, if
I wrote a Python program with Tkinter how would that program be packaged to be
installed and run on a computer?
Thanks,
Chris Nally
Louisville, Kentucky
------_=_NextPart_001_01C1516F.66A343C0--
From alan.gauld@bt.com Wed Oct 10 10:45:07 2001
From: alan.gauld@bt.com (alan.gauld@bt.com)
Date: Wed, 10 Oct 2001 10:45:07 +0100
Subject: [Tutor] running programs
Message-ID: <5104D4DBC598D211B5FE0000F8FE7EB20E66BFD1@mbtlipnt02.btlabs.bt.co.uk>
> most common option is to simply install python on that
> computer. If you want to save hd space, forget it:
> python is small and in py2exe and such
> it's simply packaged up into an executable - you don't
> save any space anyway.
For a single program that's not quite true since the
installers only install the barest bits of python needed.
(NO docs and only a few libs/modules) But if you install
several such programs you will conversely wind up taking
more space than if you just installed Python because you
get the same core elements installed multiple times!!
Finally, as I was going to add in my last message just
before Oulooks send key caught me out... You can always
combine the Python installer with your program as a kind
of super set installer. In fact some of the fancier installer
software would allow you to check the registry to see if
Python was already there and adapt as necessary.
Alan g
From blakew@sonainnovations.com Wed Oct 10 14:23:35 2001
From: blakew@sonainnovations.com (Blake Winton)
Date: Wed, 10 Oct 2001 09:23:35 -0400
Subject: [Tutor] help ['import' failing?]
References:
Message-ID: <005e01c1518e$c418a580$d6d35fd8@quintessential>
Danny Yoo wrote:
> > from docviewdoc import Docviewdoc
Searching for this line on Google gives a link to a subpage of:
http://stage.linuxports.com/pyqt/book1.htm
Which is what I followed to get an understanding of what's going on.
> Is docviewdoc.py something that you've written, or is a package that
> someone else has written?
It's a file they have created earlier in the tutorial.
It seems like he's jumped into the middle of the tutorial, and doesn't have
the files from the earlier sections.
To make things worse, there doesn't seem to be a zip file of all the code.
In a private conversation, Danny mentioned that perhaps someone on the
tutor list has worked their way through that tutorial, and might have
the code already typed out... So I'm posting this to the tutors, and
asking if anyone has the code.
Thanks,
Blake.
From dyoo@hkn.eecs.berkeley.edu Wed Oct 10 19:12:34 2001
From: dyoo@hkn.eecs.berkeley.edu (Danny Yoo)
Date: Wed, 10 Oct 2001 11:12:34 -0700 (PDT)
Subject: [Tutor] Help
In-Reply-To:
Message-ID:
On Tue, 9 Oct 2001, Glauco Silva wrote:
> I would like to know how i can to do one Scrollbar to be linked with
> two Listbox if it's possible . Thank you Glauco
According to the documentation on the Scrollbar widget:
http://www.pythonware.com/library/tkinter/introduction/scrollbar.htm
we can connect a Scrollbar to a single listbox by configuring it. If we
look at their example at:
http://www.pythonware.com/library/tkinter/introduction/x7583-patterns.htm
scrollbar.config(command=listbox.yview)
A scrollbar interacts with its environment by calling back the "command"
function whenever we fiddle with the scrollbar. At first glance, it looks
like a scrollbar can only be connected to one callback, so that appears to
limit us to one widget.
However, nothing stops us from having that callback do something to two
things! Here's a small utility class I cooked up to make this easier:
it's a callback-maker that ties two preexisting callbacks together in one
bundle:
###
class TieTwoCallbacks:
def __init__(self, callback1, callback2):
self.callback1, self.callback2 = callback1, callback2
def __call__(self, *args):
apply(self.callback1, args)
apply(self.callback2, args)
###
To get a feel for what this is doing, here's a small sample run with some
non-GUI elements:
###
>>> def greeting(name): print "hello", name
...
>>> def farewell(name): print "goodbye", name
...
>>> a_chance_meeting = TieTwoCallbacks(greeting, farewell)
>>> a_chance_meeting('glauco silva')
hello glauco silva
goodbye glauco silva
###
With this, we can imagine configuring your scrollbar like this:
###
composite_callback = TieTwoCallbacks(listbox1.yview,
listbox2.yview)
scrollbar.config(command=composite_callback)
###
so that when we move the scrollbar, that scrollbar will call our
composite_callback. And since the composite_scrollback knows about
listbox1.yview and listbox2.yview, it can yell at both of them.
We can have even more fun: once we have something that ties together two
things, we can tie together multiple things!
###
>>> def handshake(dont_care): print "Let's shake!"
...
>>> another_chance_meeting = TieTwoCallbacks(greeting,
... TieTwoCallbacks(handshake, farewell))
>>> another_chance_meeting('guido')
hello guido
Let's shake!
goodbye guido
###
However, this is completely untested code --- I haven't seen how this will
work with listboxes. *grin* If you have questions about the code above,
please feel free to ask.
From james2dope@yahoo.com Wed Oct 10 21:32:42 2001
From: james2dope@yahoo.com (james middendorff)
Date: Wed, 10 Oct 2001 13:32:42 -0700 (PDT)
Subject: [Tutor] help
Message-ID: <20011010203242.81598.qmail@web13906.mail.yahoo.com>
--0-476770287-1002745962=:79170
Content-Type: text/plain; charset=us-ascii
I have been trying to get this to work but everytime I run it and type quit, it prints what I want it to but it also prints my error message as well? this is my code so far can someone explain what I am doing wrong thanks!
import os, sys
try:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
print "goodbye"
sys.exit()
inp = open(filename, "rw")
for line in inp.readlines():
print line
inp.close()
except:
IOError
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
---------------------------------
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-476770287-1002745962=:79170
Content-Type: text/html; charset=us-ascii
I have been trying to get this to work but everytime I run it and type quit, it prints what I want it to but it also prints my error message as well? this is my code so far can someone explain what I am doing wrong thanks!
import os, sys
try:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
print "goodbye"
sys.exit()
inp = open(filename, "rw")
for line in inp.readlines():
print line
inp.close()
except:
IOError
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-476770287-1002745962=:79170--
From ignacio@openservices.net Wed Oct 10 21:47:01 2001
From: ignacio@openservices.net (Ignacio Vazquez-Abrams)
Date: Wed, 10 Oct 2001 16:47:01 -0400 (EDT)
Subject: [Tutor] help
In-Reply-To: <20011010203242.81598.qmail@web13906.mail.yahoo.com>
Message-ID:
On Wed, 10 Oct 2001, james middendorff wrote:
> I have been trying to get this to work but everytime I run it and type quit, it prints what I want it to but it also prints my error message as well? this is my code so far can someone explain what I am doing wrong thanks!
>
> import os, sys
> try:
> filename = raw_input("whats the file?('quit' to quit)")
> if filename == 'quit':
> print "goodbye"
> sys.exit()
> inp = open(filename, "rw")
> for line in inp.readlines():
> print line
> inp.close()
>
> except:
> IOError
> print "Error: there is no file there!"
That's because sys.exit() raises SystemExit. Use 'except IOError:' to focus
your exception handling. While you're at it, get rid of the loose 'IOError' in
your exception handler.
--
Ignacio Vazquez-Abrams
From james2dope@yahoo.com Thu Oct 11 00:05:26 2001
From: james2dope@yahoo.com (james middendorff)
Date: Wed, 10 Oct 2001 16:05:26 -0700 (PDT)
Subject: [Tutor] help
Message-ID: <20011010230526.49352.qmail@web13908.mail.yahoo.com>
--0-667536255-1002755126=:49331
Content-Type: text/plain; charset=us-ascii
I have fixed my last post but I do have a question, I would like to keep looping this over and over until you type quit,thanks for the help!
import os, sys
try:
while 1:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
sys.exit()
inp = open(filename, "r")
for line in inp.readlines():
print line
inp.close()
except IOError:
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
---------------------------------
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-667536255-1002755126=:49331
Content-Type: text/html; charset=us-ascii
I have fixed my last post but I do have a question, I would like to keep looping this over and over until you type quit,thanks for the help!
import os, sys
try:
while 1:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
sys.exit()
inp = open(filename, "r")
for line in inp.readlines():
print line
inp.close()
except IOError:
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-667536255-1002755126=:49331--
From james2dope@yahoo.com Thu Oct 11 00:05:31 2001
From: james2dope@yahoo.com (james middendorff)
Date: Wed, 10 Oct 2001 16:05:31 -0700 (PDT)
Subject: [Tutor] help
Message-ID: <20011010230531.12021.qmail@web13906.mail.yahoo.com>
--0-1370392546-1002755131=:9199
Content-Type: text/plain; charset=us-ascii
I have fixed my last post but I do have a question, I would like to keep looping this over and over until you type quit,thanks for the help!
import os, sys
try:
while 1:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
sys.exit()
inp = open(filename, "r")
for line in inp.readlines():
print line
inp.close()
except IOError:
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
---------------------------------
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-1370392546-1002755131=:9199
Content-Type: text/html; charset=us-ascii
I have fixed my last post but I do have a question, I would like to keep looping this over and over until you type quit,thanks for the help!
import os, sys
try:
while 1:
filename = raw_input("whats the file?('quit' to quit)")
if filename == 'quit':
sys.exit()
inp = open(filename, "r")
for line in inp.readlines():
print line
inp.close()
except IOError:
print "Error: there is no file there!"
"I would kill everyone in this room
for a drop of sweet beer."
----Homer Simpson----
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
--0-1370392546-1002755131=:9199--
From ignacio@openservices.net Thu Oct 11 00:10:47 2001
From: ignacio@openservices.net (Ignacio Vazquez-Abrams)
Date: Wed, 10 Oct 2001 19:10:47 -0400 (EDT)
Subject: [Tutor] help
In-Reply-To: <20011010230531.12021.qmail@web13906.mail.yahoo.com>
Message-ID:
On Wed, 10 Oct 2001, james middendorff wrote:
>
> I have fixed my last post but I do have a question, I would like to keep looping this over and over until you type quit,thanks for the help!
>
> import os, sys
> try:
> while 1:
> filename = raw_input("whats the file?('quit' to quit)")
> if filename == 'quit':
> sys.exit()
>
> inp = open(filename, "r")
> for line in inp.readlines():
> print line
> inp.close()
>
> except IOError:
> print "Error: there is no file there!"
Put the try/except inside the while.
--
Ignacio Vazquez-Abrams
From urnerk@qwest.net Thu Oct 11 04:45:39 2001
From: urnerk@qwest.net (Kirby Urner)
Date: Wed, 10 Oct 2001 20:45:39 -0700
Subject: [Tutor] help
In-Reply-To: <20011010230531.12021.qmail@web13906.mail.yahoo.com>
Message-ID: <4.2.0.58.20011010203117.00bf1870@pop3.norton.antivirus>
At 04:05 PM 10/10/2001 -0700, james middendorff wrote:
>I have fixed my last post but I do have a question, I would like to keep
>looping this over and over until you type quit,thanks for the help!
What might trigger an ioerror is the program tries to
open a file that doesn't exist. That's all you need
to trap with the try: except: syntax.
The stuff about raw_input doesn't really need to be
in a try block.
In other words, this would work better:
def getfile():
import os, sys
while 1: # endless loop
filename = raw_input("What file? ('q' to quit): ")
if filename == 'q':
break # escape from loop
try:
inp = open(filename,"r")
print # blank line
for line in inp.readlines():
print line, # note comma to suppress extra \n
except IOError:
print "That's not a real file!"
# upon exiting to loop, flow continues here
sys.exit() # I comment this out cuz I'm in shell mode
>>> getfile()
What file? ('q' to quit): duh.txt
That's not a real file!
What file? ('q' to quit): readme.txt
This is Python version 2.2
==========================
Copyright (c) 2001 Python Software Foundation.
All rights reserved.
Copyright (c) 2000 BeOpen.com.
All rights reserved.
...
Kirby
From wmperry@swbell.net Thu Oct 11 05:01:04 2001
From: wmperry@swbell.net (William Perry)
Date: Wed, 10 Oct 2001 23:01:04 -0500
Subject: [Tutor] Help
In-Reply-To:
References:
Message-ID: <200110102301040710.0D6C71F4@mail.swbell.net>
in Mark Lutz's Programing Python example 7-31 he uses 2 linked scrollbars (sliders) to demonstrate useage. This might help (??)
*********** REPLY SEPARATOR ***********
On 10/10/01 at 11:12 AM Danny Yoo wrote:
>On Tue, 9 Oct 2001, Glauco Silva wrote:
>
>> I would like to know how i can to do one Scrollbar to be linked with
>> two Listbox if it's possible . Thank you Glauco
>
>
From dyoo@hkn.eecs.berkeley.edu Thu Oct 11 08:00:00 2001
From: dyoo@hkn.eecs.berkeley.edu (Danny Yoo)
Date: Thu, 11 Oct 2001 00:00:00 -0700 (PDT)
Subject: [Tutor] Help
In-Reply-To: <200110102301040710.0D6C71F4@mail.swbell.net>
Message-ID:
On Wed, 10 Oct 2001, William Perry wrote:
> in Mark Lutz's Programing Python example 7-31 he uses 2 linked
> scrollbars (sliders) to demonstrate useage. This might help (??)
Cool; can anyone post that example up? I've donated my copy of
Programming Python away... guess I know what my next book purchase will be
tomorrow... *grin*
From agauld@crosswinds.net Thu Oct 11 08:13:56 2001
From: agauld@crosswinds.net (agauld@crosswinds.net)
Date: Thu, 11 Oct 2001 08:13:56 +0100
Subject: [Tutor] ONline tutor
Message-ID: <07210120359994@mailth4.freenet.co.uk>
My Crosswinds site is now fully restored but as previously
mentioned I am now moving the master site to a new service
provider.
The new location will be:
http://www.freenetpages.co.uk/hp/alan.gauld/
This site has:
- no adverts
- allows ftp access(much faster than web/http)
and, within the UK at least, is a lot faster than crosswinds.
If somebody in the US could confirm that speed is
acceptable from there then I will complete the transfer
process. (The English and Spanish sites are already there.)
Alan G.
From ignacio@openservices.net Thu Oct 11 08:36:37 2001
From: ignacio@openservices.net (Ignacio Vazquez-Abrams)
Date: Thu, 11 Oct 2001 03:36:37 -0400 (EDT)
Subject: [Tutor] ONline tutor
In-Reply-To: <07210120359994@mailth4.freenet.co.uk>
Message-ID:
On Thu, 11 Oct 2001 agauld@crosswinds.net wrote:
> My Crosswinds site is now fully restored but as previously
> mentioned I am now moving the master site to a new service
> provider.
>
> The new location will be:
>
> http://www.freenetpages.co.uk/hp/alan.gauld/
>
> This site has:
> - no adverts
I think I speak for everyone but advertisers when I say WOOT!
> - allows ftp access(much faster than web/http)
> and, within the UK at least, is a lot faster than crosswinds.
> If somebody in the US could confirm that speed is
> acceptable from there then I will complete the transfer
> process. (The English and Spanish sites are already there.)
Good responsiveness. A bit spotty on downloading the tarball, but the HTML and
images were quite quick via ADSL.
--
Ignacio Vazquez-Abrams
From nhytro-python@web.de Thu Oct 11 10:27:32 2001
From: nhytro-python@web.de (Sharriff Aina)
Date: Thu, 11 Oct 2001 11:27:32 +0200
Subject: [Tutor] PyTix examples/Tutorials
Message-ID: <200110110927.f9B9RWu18324@mailgate5.cinetic.de>
Hello!
can anyone point me to a good PyTix tutorial? the PyTix homepage does not help a bit, it refers one to the TCL/TK homepage. If someone hast a simple "Helloworld" using a mixture of Tkinter an TIX it would suffice also.
Thanks so much
Sharriff
_______________________________________________________________________
1.000.000 DM gewinnen - kostenlos tippen - http://millionenklick.web.de
IhrName@web.de, 8MB Speicher, Verschluesselung - http://freemail.web.de
From toodles@yifan.net Thu Oct 11 12:10:13 2001
From: toodles@yifan.net (Andrew Wilkins)
Date: Thu, 11 Oct 2001 19:10:13 +0800
Subject: [Tutor] ONline tutor
References:
Message-ID: <001701c15245$4d7ec820$0300a8c0@sun>
> I think I speak for everyone but advertisers when I say WOOT!
I'll second that!
> Good responsiveness. A bit spotty on downloading the tarball, but the HTML
and
> images were quite quick via ADSL.
And that. (Perth, Western Australia also on ADSL)
Andrew
From rick@niof.net Thu Oct 11 15:23:45 2001
From: rick@niof.net (Rick Pasotto)
Date: Thu, 11 Oct 2001 10:23:45 -0400
Subject: [Tutor] Help
In-Reply-To: <200110102301040710.0D6C71F4@mail.swbell.net>
References: <200110102301040710.0D6C71F4@mail.swbell.net>
Message-ID: <20011011102345.A13058@tc.niof.net>
On Wed, Oct 10, 2001 at 11:01:04PM -0500, William Perry wrote:
> in Mark Lutz's Programing Python example 7-31 he uses 2 linked
> scrollbars (sliders) to demonstrate useage. This might help (??)
But the question was about *one* scrollbar linked to two listboxes.
> *********** REPLY SEPARATOR ***********
>
> On 10/10/01 at 11:12 AM Danny Yoo wrote:
>
> >On Tue, 9 Oct 2001, Glauco Silva wrote:
> >
> >> I would like to know how i can to do one Scrollbar to be linked
> >> with two Listbox if it's possible . Thank you Glauco
--
Hence, if anything is self-evident, it is this: law is the
organization of the natural right to legitimate self-defense, it
is the substitution of collective force for individual forces, to
act in the sphere in which they have the right to act, to do what
they have the right to do: to guarantee security of person,
liberty, and property rights, to cause justice to reign over all.
-- Fr�d�ric Bastiat (1801-1850)
Rick Pasotto rickp@telocity.com http://www.niof.net
From lonetwin Thu Oct 11 17:28:56 2001
From: lonetwin (lonetwin)
Date: Thu, 11 Oct 2001 21:58:56 +0530 (IST)
Subject: [Tutor] Variables in Threaded functions
Message-ID:
Hi all ye good people,
I'm kinda new to threaded programming in python (in any language
for that matter !!). I'd like somebody to clear this up for me.
I want to write a class that inherits from threading.Thread,
whose run() function runs a loop that looks at a self.sequence,
if there is something left in that sequence it goes and does
something(self.sequence.pop()). Now a limited (say 3) threads would
execute. My understanding is (correct me if I'm wrong) all the threads
share the same self.sequence (if they don't how do I make them share a
sequence ....without having to put in a global sequence ??) and also
I'm uncertain about the implications of doing such things (shud I use
locks ?? ...if I shud....how do I do that ??)
Basically I want someone to explain how this code works and the
implications of doing such things on a larger scale:
========================================================================
import threading
import time
class Strand(threading.Thread):
bag = range(100)
def __init__(self):
threading.Thread.__init__(self)
def run(self):
while len(self.bag):
print self.bag.pop(),
def main():
Rope = []
for x in range(3):
thread = Strand()
Rope.append(thread)
for thread in Rope:
thread.start()
print done
if __name__ == '__main__':
main()
--
----------------------------------------------
Every oak tree started out as a
couple of nuts who stood their ground.
Anonymous
----------------------------------------------
From arcege@speakeasy.net Thu Oct 11 17:58:35 2001
From: arcege@speakeasy.net (Michael P. Reilly)
Date: Thu, 11 Oct 2001 12:58:35 -0400
Subject: [Tutor] Help
In-Reply-To: ; from gbcs1978@hotmail.com on Tue, Oct 09, 2001 at 03:07:23PM -0300
References:
Message-ID: <20011011125835.A982@speakeasy.net>
On Tue, Oct 09, 2001 at 03:07:23PM -0300, Glauco Silva wrote:
> I would like to know how i can to do one Scrollbar to be linked with
> two Listbox if it's possible .
It's a little tricky, but you can do it. Unfortunately, there isn't
great documentation even from the Tk side on the scrollbar callbacks
(the documentation is there.. just not always straightforward).
You need to make a new callback so the scrollbar calls the methods of
both listboxes. Something like:
import os
from Tkinter import *
from Tkinter import _cnfmerge
class DoubleListbox(Frame):
def __init__(self, master=None, cnf={}, **kws):
# combine the configuration options into one
cnf = _cnfmerge( (cnf, kws) )
Frame.__init__(self, master, cnf)
self.sb = Scrollbar(self, command=self._scrollbar_from_sb)
self.lb1 = Listbox(self, selectmode=SINGLE,
yscrollcommand=self.self.sb.set)
self.lb2 = Listbox(self, selectmode=SINGLE,
yscrollcommand=self.self.sb.set)
# here, we put the scrollbar on the extreme right of the frame
self.sb.pack(side=RIGHT, fill=Y, expand=YES)
self.lb1.pack(side=LEFT, fill=BOTH, expand=YES)
self.lb2.pack(side=RIGHT, fill=BOTH, expand=YES)
def _scrollbar_from_sb(self, *args):
# if the argument from set is "scroll", then use the yview_scroll method
# otherwise use the yview_moveto method of both listboxes
meth_name = 'yview_' + args[0]
args = args[1:]
for obj in (self.lb1, self.lb2):
meth = getattr(obj, meth_name)
apply(meth, args)
def _test():
root = Tk()
dbllb = DoubleListbox(root, height=50, width=20)
for file in os.listdir(os.curdir):
if os.path.isdir(file):
dbllb.lb1.insert(END, '%s/' % file)
else:
dbllb.lb2.insert(END, file)
dbllb.pack(fill=BOTH, expand=YES)
Button(root, text="Quit", command=root.quit).pack(side=BOTTOM)
root.mainloop()
if __name__ == '__main__':
_test()
Hope this helps.
-Arcege
--
+----------------------------------+-----------------------------------+
| Michael P. Reilly | arcege@speakeasy.net |
| Ailment info: http://www.speakeasy.org/~arcege/michaelwatch.html |
From jerryl@europa.com Thu Oct 11 18:07:05 2001
From: jerryl@europa.com (Jerry Lake)
Date: Thu, 11 Oct 2001 10:07:05 -0700
Subject: [Tutor] learning projects
In-Reply-To: <20011011125835.A982@speakeasy.net>
Message-ID: <000001c15277$287ab200$0103670a@europa.com>
Can anyone give me some advise
as to some projects to try with
python that will help me gain
a better understanding of it as
well as programming in general
I pretty much have access to any
type of setup I need
Thanks,
Jerry Lake
Interface Engineering Technician
From shalehperry@home.com Thu Oct 11 18:12:47 2001
From: shalehperry@home.com (Sean 'Shaleh' Perry)
Date: Thu, 11 Oct 2001 10:12:47 -0700 (PDT)
Subject: [Tutor] learning projects
In-Reply-To: <000001c15277$287ab200$0103670a@europa.com>
Message-ID:
On 11-Oct-2001 Jerry Lake wrote:
> Can anyone give me some advise
> as to some projects to try with
> python that will help me gain
> a better understanding of it as
> well as programming in general
>
> I pretty much have access to any
> type of setup I need
>
find some thing you use and reimplement it in python. Or look around the web
for CS class programming assignments and do them in python.
From rob@jam.rr.com Thu Oct 11 18:24:42 2001
From: rob@jam.rr.com (Rob Andrews)
Date: Thu, 11 Oct 2001 12:24:42 -0500
Subject: [Tutor] learning projects
In-Reply-To: <000001c15277$287ab200$0103670a@europa.com>
References: <20011011125835.A982@speakeasy.net>
Message-ID: <3BC58F8A.7940.10470A2@localhost>
On 11 Oct 2001, at 10:07, Jerry Lake wrote:
> Can anyone give me some advise
> as to some projects to try with
> python that will help me gain
> a better understanding of it as
> well as programming in general
>
Useless Python:
http://www.lowerstandard.com/python/
Lots of projects and ideas, complete with a ton of code to play with. You
can even change someone else's code around, send it in, and see it
posted on the site. Plus, the site features programming contest problems
and a pretty decent collection of links.
Rob
From lkvam@venix.com Thu Oct 11 18:35:30 2001
From: lkvam@venix.com (Lloyd Kvam)
Date: Thu, 11 Oct 2001 13:35:30 -0400
Subject: [Tutor] learning projects
References: <000001c15277$287ab200$0103670a@europa.com>
Message-ID: <3BC5D862.24FCCCCF@venix.com>
This site looks good to me. A lot depends on your interests.
http://www.freenetpages.co.uk/hp/alan.gauld/
Many of the Python books include lots of sample code. The oreilly site has the samples from "Python Programming on Win32". If you are stuck in Windows, this book is great. The sample code includes large enough chunks to represent fairly real
programs. I've adopted many ideas that were shown in their accounting examples.
Jerry Lake wrote:
>
> Can anyone give me some advise
> as to some projects to try with
> python that will help me gain
> a better understanding of it as
> well as programming in general
>
> I pretty much have access to any
> type of setup I need
>
> Thanks,
>
> Jerry Lake
> Interface Engineering Technician
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
--
Lloyd Kvam
Venix Corp.
1 Court Street, Suite 378
Lebanon, NH 03766-1358
voice: 603-443-6155
fax: 801-459-9582
From lkvam@venix.com Thu Oct 11 18:45:39 2001
From: lkvam@venix.com (Lloyd Kvam)
Date: Thu, 11 Oct 2001 13:45:39 -0400
Subject: [Tutor] learning projects
References: <000001c15277$287ab200$0103670a@europa.com> <3BC5D862.24FCCCCF@venix.com>
Message-ID: <3BC5DAC3.FDDDC4E3@venix.com>
I forgot another very good site:
http://gnosis.cx/publish/tech_index.html
Most of these articles were written for other sites & publications. I have found them to be very useful for improving my Python skills.
Lloyd Kvam wrote:
>
> This site looks good to me. A lot depends on your interests.
> http://www.freenetpages.co.uk/hp/alan.gauld/
>
> Many of the Python books include lots of sample code. The oreilly site has the samples from "Python Programming on Win32". If you are stuck in Windows, this book is great. The sample code includes large enough chunks to represent fairly real
> programs. I've adopted many ideas that were shown in their accounting examples.
>
> Jerry Lake wrote:
> >
> > Can anyone give me some advise
> > as to some projects to try with
> > python that will help me gain
> > a better understanding of it as
> > well as programming in general
> >
> > I pretty much have access to any
> > type of setup I need
> >
> > Thanks,
> >
> > Jerry Lake
> > Interface Engineering Technician
> >
> > _______________________________________________
> > Tutor maillist - Tutor@python.org
> > http://mail.python.org/mailman/listinfo/tutor
>
> --
> Lloyd Kvam
> Venix Corp.
> 1 Court Street, Suite 378
> Lebanon, NH 03766-1358
>
> voice: 603-443-6155
> fax: 801-459-9582
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
--
Lloyd Kvam
Venix Corp.
1 Court Street, Suite 378
Lebanon, NH 03766-1358
voice: 603-443-6155
fax: 801-459-9582
From boud@valdyas.org Thu Oct 11 20:03:16 2001
From: boud@valdyas.org (Boudewijn Rempt)
Date: Thu, 11 Oct 2001 21:03:16 +0200
Subject: [Tutor] Variables in Threaded functions
In-Reply-To:
References:
Message-ID: <200110111903.f9BJ3Mx10101@calcifer.valdyas.org>
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On Thursday 11 October 2001 18:28, lonetwin wrote:
> =09 I want to write a class that inherits from threading.Thread,
> whose run() function runs a loop that looks at a self.sequence,
> if there is something left in that sequence it goes and does
> something(self.sequence.pop()). Now a limited (say 3) threads would
> execute. My understanding is (correct me if I'm wrong) all the threads
> share the same self.sequence (if they don't how do I make them share a
> sequence ....without having to put in a global sequence ??) and also
> I'm uncertain about the implications of doing such things (shud I use
> locks ?? ...if I shud....how do I do that ??)
If you want all threads to share something, you do need to have an
object that is accessible to all of them. However, accessing a shared
object from more than one thread at a time is a recipe for disaster,
so you need to create a lock object, and acquire() that lock before
every access.
This is how I rewrote your script:
- ---
import threading, time
class Strand(threading.Thread):
def __init__(self, bag, lock):
"""The bag and the lock are shared objects,
passed to the threads in their constructors. Another
strategy is to make them global, but that's not half
as neat."""
threading.Thread.__init__(self)
self.bag=3Dbag
self.lock=3Dlock
def run(self):
# getName() tells us which thread is started
print "Started " + self.getName()
# We keep running until something gives us a break
while 1:
# We acquire the lock - in Java objects can be their own
# locks, and you can synchronize() on an object. In Python
# you need a separate lock object, and explicitly
# acquire() that lock. If one thread accesses the
# resources the lock is supposed to protect, without
# acquiring it, then your concurrency is hosed. Caveat
# delendor.=20
self.lock.acquire()
# Always encapsulate usage of the locked object in a
# try... finally block: if the lock isn't released through
# some exception, all other threads would be blocked.
try:
# If the bag is empty, we quit.
if len(self.bag) =3D=3D 0:
break
# Print the popped value
print "thread", self.getName(), ": ", self.bag.pop()
finally:
# Whatever happens, always release the lock.
self.lock.release()
# Sleep a bit. A timeslice is long enough to pop the whole
# bag in the first timeslice of the first thread.
time.sleep(1)
def main():
Rope =3D []
# The shared object and the shared lock
sharedBagOfGoodies =3D range(100)
sharedBagLock =3D threading.Lock()
=20
for x in range(3):
thread =3D Strand(sharedBagOfGoodies, sharedBagLock)
Rope.append(thread)
=20
for thread in Rope:
print thread.getName()
thread.start()
=20
print "done"
if __name__ =3D=3D '__main__':
main()
- ---
> Basically I want someone to explain how this code works and the
> implications of doing such things on a larger scale:
>
Threaded programming on a large scale is _difficult_. I'm not kidding,
my day job is working on an agent platform that can handle thousands
of concurrent agents and system processes, all implemented using threads
(except that the agents themselves share a pool of threads and run
cooperatively), I am continually running into threading problems.
On the other hand, it's fun, too. You might like my article at Informit=20
on Python an microthreads (search for rempt - they don't provide direct
links - http://www.informit.com).
Another nice link:=20
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65202/index_txt
In this simple example, you won't encounter any race conditions by not
locking, but that is no indication of future results.
- --=20
Boudewijn Rempt | http://www.valdyas.org
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From dyoo@hkn.eecs.berkeley.edu Thu Oct 11 20:14:15 2001
From: dyoo@hkn.eecs.berkeley.edu (Danny Yoo)
Date: Thu, 11 Oct 2001 12:14:15 -0700 (PDT)
Subject: [Tutor] ONline tutor
In-Reply-To: <001701c15245$4d7ec820$0300a8c0@sun>
Message-ID:
On Thu, 11 Oct 2001, Andrew Wilkins wrote:
> > I think I speak for everyone but advertisers when I say WOOT!
>
> I'll second that!
>
> > Good responsiveness. A bit spotty on downloading the tarball, but
> the HTML and > images were quite quick via ADSL.
>
> And that. (Perth, Western Australia also on ADSL)
Feels fast here (Stanford, CA) too! Looks great!
From rufmetal@home.com Fri Oct 12 04:18:56 2001
From: rufmetal@home.com (Chris Keelan)
Date: Thu, 11 Oct 2001 22:18:56 -0500
Subject: [Tutor] Strange modulus problem
Message-ID: <01101122185600.00949@tygesen>
I'm working on a bit of code to determine all of the factors up to and
including a number entered by the user. Here's my code:
#!/usr/bin/python
import string
num=raw_input("Enter a number: ")
num_int=string.atoi(num)
factor_range= range(1, num_int + 1)
for item in factor_range:
if num_int % item > 0:
factor_range.remove(item)
print 'The factors are %s' % factor_range
But when I run it, I get the following weird output:
>>Enter a number: 6
The factors are [1, 2, 3, 5, 6]
Why doesn't '5' fail the if test and get removed? If I modify the code so
that it prints the modulus of each item, 5 correctly evalutates to '1'. What
gives?
- Chris
From urnerk@qwest.net Fri Oct 12 04:22:57 2001
From: urnerk@qwest.net (Kirby Urner)
Date: Thu, 11 Oct 2001 20:22:57 -0700
Subject: [Tutor] Strange modulus problem
In-Reply-To: <01101122185600.00949@tygesen>
Message-ID: <4.2.0.58.20011011200732.00a6ec10@pop3.norton.antivirus>
>
>Why doesn't '5' fail the if test and get removed? If I modify
>the code so that it prints the modulus of each item, 5 correctly
>evalutates to '1'. What gives?
>
>- Chris
This has to do with iterating over the object you're
also modifying.
The code below works because it iterates over a copy
of factor_range (the effect of putting [:] after it):
>>> def factors(n):
factor_range = range(1, n + 1)
for item in factor_range[:]:
if n % item:
factor_range.remove(item)
return factor_range
>>> factors(6)
[1, 2, 3, 6]
>>> factors(20)
[1, 2, 4, 5, 10, 20]
(Note also that n%item is true if non-zero, so you
don't really need the additional >0).
In the your way of doing it, you don't actually get to
test all the numbers in the range, because you yank an
offender out of the line-up, shortening the list, so
when the loop comes around and it iterates to the
"next" item, it's hitting against a foreshortened list,
meaning it skips over a value you wish it hadn't.
You can study this behavior by inserting a line that
prints the item being tested:
>>> def factors(n):
factor_range = range(1, n + 1)
for item in factor_range: # not a copy
print item # debug print
if n % item:
factor_range.remove(item)
return factor_range
>>> factors(10)
1
2
3
5
6
8
10
[1, 2, 4, 5, 7, 9, 10]
You see that 4 wasn't tested, because the program yanks
3 (not a factor), and so the next candidate it hits if 5.
Likewise, 7 and 9 sneak through.
This is a common programming error in Python and you're
lucky to stumble across it in such an illuminating
manner. It's very good to make mistakes of this kind
-- very text book. You have a promising career as a
Pythoneer ahead of you (pardon the fortune cookie).
Kirby
From toodles@yifan.net Fri Oct 12 04:35:41 2001
From: toodles@yifan.net (Andrew Wilkins)
Date: Fri, 12 Oct 2001 11:35:41 +0800
Subject: [Tutor] Strange modulus problem
References: <01101122185600.00949@tygesen>
Message-ID: <000c01c152ce$f8a77830$0300a8c0@sun>
I think what I have to say is right, if I'm not someone please correct me :)
> I'm working on a bit of code to determine all of the factors up to and
> including a number entered by the user. Here's my code:
>
> #!/usr/bin/python
>
> import string
>
> num=raw_input("Enter a number: ")
> num_int=string.atoi(num)
>
> factor_range= range(1, num_int + 1)
>
> for item in factor_range:
> if num_int % item > 0:
> factor_range.remove(item)
"for" goes through the indices 0..len(factor_range)
As you remove each item it decreases the size of factor_range, and the index
that for points to next will contain something else.
Example:
>>> test_range=range(10)
>>> for i in test_range:
print i,test_range
test_range.remove(i)
0 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
2 [1, 2, 3, 4, 5, 6, 7, 8, 9]
4 [1, 3, 4, 5, 6, 7, 8, 9]
6 [1, 3, 5, 6, 7, 8, 9]
8 [1, 3, 5, 7, 8, 9]
So as you can see in the 2nd iteration it is pointing to index 1 as it
should be, but this now points to "2".
So to fix this you could do it one of these (untested) ways:
1) Preserve what you've done already
factor_range=range(1,num_int+1)
loop_range=factor_range[:] #copy contents
for item in loop_range:
if num_int % item > 0:
loop_range.remove(item)
2) Do it the way I prefer to do it :)
factors=[]
for i in range(1,num_int+1):
if num_int%i==0: factors.append(i)
...I'm sure there's still more ways.
> Why doesn't '5' fail the if test and get removed? If I modify the code so
> that it prints the modulus of each item, 5 correctly evalutates to '1'.
What
> gives?
>>> fr=range(1,7)
>>> for item in fr:
print item,fr
if 6%item>0: fr.remove(item)
1 [1, 2, 3, 4, 5, 6]
2 [1, 2, 3, 4, 5, 6]
3 [1, 2, 3, 4, 5, 6]
4 [1, 2, 3, 4, 5, 6]
6 [1, 2, 3, 5, 6]
It's not even looking at 5 :)
It gets to "4" and removes it, thus bringing the next index to point to "6".
HTH
Andrew
>
> - Chris
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
From lonetwin@yahoo.com Fri Oct 12 11:08:35 2001
From: lonetwin@yahoo.com (lonetwin)
Date: Fri, 12 Oct 2001 15:38:35 +0530
Subject: [Tutor] Variables in Threaded functions
In-Reply-To: <200110111903.f9BJ3Mx10101@calcifer.valdyas.org>
References: <200110111903.f9BJ3Mx10101@calcifer.valdyas.org>
Message-ID: <01101215383501.21081@mercury.worli>
Hi everybody,
Thanx Boudewijn, for the quick answer. Now that I have fixed what I was
trying to do...I have some more questions for you (an' everybody who might
want to answer).
You wrote:
> If you want all threads to share something, you do need to have an
> object that is accessible to all of them. However, accessing a shared
> object from more than one thread at a time is a recipe for disaster,
> so you need to create a lock object, and acquire() that lock before
> every access.
Right, I though as much.
*********************************************
> This is how I rewrote your script:
> ----
> import threading, time
>
> class Strand(threading.Thread):
>
> def __init__(self, bag, lock):
> """The bag and the lock are shared objects,
> passed to the threads in their constructors. Another
> strategy is to make them global, but that's not half
> as neat."""
> threading.Thread.__init__(self)
> self.bag=bag
> self.lock=lock
<-------------------------snip-------------------------->
Question 1: why is bag passed to Strand ??....what if I bag belongs to be
the class ....like I did in my initial proggy ...is this a bad-thing in any
manner vvvvvvvvvvv
class Strand(threading.thread):
bag = range(100)
def __init__(self, lock):
.....
.....
<-------------------------/snip---------------------------->
> def run(self):
> # getName() tells us which thread is started
> print "Started " + self.getName()
> # We keep running until something gives us a break
> while 1:
> # We acquire the lock - in Java objects can be their own
> # locks, and you can synchronize() on an object. In Python
> # you need a separate lock object, and explicitly
> # acquire() that lock. If one thread accesses the
> # resources the lock is supposed to protect, without
> # acquiring it, then your concurrency is hosed. Caveat
> # delendor.
> self.lock.acquire()
> # Always encapsulate usage of the locked object in a
> # try... finally block: if the lock isn't released through
> # some exception, all other threads would be blocked.
> try:
> # If the bag is empty, we quit.
> if len(self.bag) == 0:
> break
> # Print the popped value
> print "thread", self.getName(), ": ", self.bag.pop()
> finally:
> # Whatever happens, always release the lock.
> self.lock.release()
<----------------------snip-------------------------------->
Question 2: Why ....
def run(self):
while 1:
self.acquire()
try:
if len(self.bag) == 0:
break
else:
doStuff()
finally:
self.lock.release()
.......
instead of ....
def run(self):
self.acquire()
try:
while len(self.bag) !=0:
doStuff()
finally:
self.lock.release()
For me, this ^^^^ reads much better....but is there something I should
know about ???
<---------------------------/snip---------------------->
> # Sleep a bit. A timeslice is long enough to pop the whole
> # bag in the first timeslice of the first thread.
> time.sleep(1)
>
> def main():
> Rope = []
> # The shared object and the shared lock
> sharedBagOfGoodies = range(100)
> sharedBagLock = threading.Lock()
>
> for x in range(3):
> thread = Strand(sharedBagOfGoodies, sharedBagLock)
> Rope.append(thread)
>
> for thread in Rope:
> print thread.getName()
> thread.start()
>
> print "done"
>
> if __name__ == '__main__':
> main()
> -------
And finally Question 3: What if I have more that one bag ?? does one lock,
lock-up all the shared objects ??....or should I lock.acquire() before every
access to any one of the shared objects ??
Hope my questions make sense...
Thanx for you patience
Peace
Steve
----------------------------------------------
Every oak tree started out as a
couple of nuts who stood their ground.
Anonymous
----------------------------------------------
From mailmgr2@i-55.com Fri Oct 12 20:09:07 2001
From: mailmgr2@i-55.com (Craig Carman)
Date: Fri, 12 Oct 2001 19:09:07
Subject: [Tutor] Thank You! & Something for you
Message-ID: PM20007:09:07 PM
This is an HTML email message. If you see this, your mail client does not support HTML messages.
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From urnerk@qwest.net Sat Oct 13 01:48:23 2001
From: urnerk@qwest.net (Kirby Urner)
Date: Fri, 12 Oct 2001 17:48:23 -0700
Subject: [Tutor] Variables in Threaded functions
In-Reply-To: <01101215383501.21081@mercury.worli>
References: <200110111903.f9BJ3Mx10101@calcifer.valdyas.org>
<200110111903.f9BJ3Mx10101@calcifer.valdyas.org>
Message-ID: <4.2.0.58.20011012172733.00c564a0@pop3.norton.antivirus>
>
> Question 1: why is bag passed to Strand ??....what if
>I bag belongs to be the class ....like I did in my initial
>proggy ...is this a bad-thing in any manner vvvvvvvvvvv
Seems a non-idiomatic use of a class variable, but
maybe it works -- I haven't tested it.
>def run(self):
> self.acquire()
> try:
> while len(self.bag) !=0:
> doStuff()
> finally:
> self.lock.release()
>
> For me, this ^^^^ reads much better....but is there something
>I should know about ???
Here your thread grabs the lock, then loops around while
the bag isn't empty, sucking it dry, then, finally, it
releases the lock. So what do the other threads get to
do? Just wait around and watch while Mr. Greedy Gut hogs
the entire bag I guess.
>And finally Question 3: What if I have more that one bag ??
>does one lock, lock-up all the shared objects ??....or should
>I lock.acquire() before every access to any one of the shared
>objects ??
>
>Hope my questions make sense...
>
>Thanx for you patience
>
>Peace
>Steve
Well, I'm not Mr. Threads (the previous respondant sounded
way more knowledgable than I), but I think you should think
of the lock as akin to the conch in 'Lord of the Flies'.
Every read that? These kids get marooned on a tropical
island and their culture gradually degenerates, but one
convention is whoever holds this big shell in meetings is
the one who gets to talk, and you pass this shell (conch)
around to control the flow of speech -- similar to a
"talking stick" in some native American traditions.
The lock is a conch, and as long as one thread has it,
the other threads block when trying to aquire it for
themselves. Whichever thread is holding the conch has
to explicitly release it, before the other would-be
aquirers have a chance.
However, as the previous respondant posted, it's up to
you to write civilized thread code that actually asks
permission before modifying data:
If one thread accesses the resources the lock
is supposed to protect, without acquiring it,
then your concurrency is hosed. Caveat delendor.
You-the-programmer put into your code where a thread
should say "pretty please". But if you code up some
bull-in-a-China-shop thread that doesn't even ask
(doesn't try to aquire) but just goes ahead and attacks
the bag, then all the other threads can do is watch in
horror. No operating system police are going to keep
the undisciplined thread from just charging around,
doing whatever damage.
In other words, the aquire(), release() convention
simply provides a mechanism whereby you can establish
a genteel arrangement among your threads, but doesn't
involve any physical placement of locks on any data
objects. Ergo, there's no question of needing multiple
locks for each object -- they're not really locked,
it's the threads that use the lock object to take
turns doing whatever.
Kirby
PS: in 'Lord of the Flies', some bullies eventually
get tired of the conch convention and break this final
rule. Some fat kid, who was holding the conch at the
time, protests, and pays with his life. A cheery book
-- they make school kids read it so they can see why
adults are so strict (left to your own devices, you'd
make dead meat of each other in no time, is the message).
From dyoo@hkn.eecs.berkeley.edu Sat Oct 13 02:52:30 2001
From: dyoo@hkn.eecs.berkeley.edu (Danny Yoo)
Date: Fri, 12 Oct 2001 18:52:30 -0700 (PDT)
Subject: [Tutor] Thank You! & Something for you [difflib in Python 2.1]
In-Reply-To: PM20007:09:07 PM
Message-ID:
On Fri, 12 Oct 2001, Craig Carman wrote:
> Choose from:
> * Figaro Design
> * Beaded Design
> * Snake Design
^^^^^
You've reached Python-tutor, which, despite its name, has very little to
do with "Python reticulatus". The name "Python" here refers to the highly
regarded "Monty Python" comedy group. I guess "Python" could also refer,
distantly, to the name of a really nice programming language.
We're a group of tutors who help each other learn how to program, and your
question has very little content. Still, even in the midst of your
confusion, we can try to help.
>From the snippet above, we could interpret that you're trying to get a
user to choose from a list of specific choices, maybe something like this:
###
What flavor of ice cream do you like the most?
Choose from the following:
* green tea
* rocky road
* vanilla
* chocolate
> Humperdinck
I don't know about Humperdinck. Please try again.
> banilla
I don't know about banilla. Please try again.
> vanilla
###
Here's one possible implementation for this alternative-choosing function:
###
def chooseAnAlternative(alternatives):
while 1:
choice = raw_input("> ")
if choice in alternatives:
return choice
print "I don't know about %s. Please try again." % choice
###
This works... but we notice that program is a little unfriendly: it
doesn't accept any misspellings. Even if someone is one letter off, our
program just clamps hands over its years and sings "I'm not listening..."
But this can be fixed! We can make this program more forgiving with the
extremely cool 'difflib' module that's new with Python 2.1:
http://python.org/doc/current/lib/module-difflib.html
difflib will, given a list of choices, try to find the very best choice,
even if the user misspells a word:
###
import difflib
def chooseAnAlternative(alternatives):
while 1:
choice = raw_input("> ")
best_match = difflib.get_close_matches(choice, alternatives, 1)
if best_match:
return best_match[0]
print "I don't know about %s. Please try again." % choice
###
Here's a small test of this improved chooseAnAlternative() function:
###
>>> flavours = ['green tea', 'rocky road', 'vanilla', 'chocolate']
>>> chooseAnAlternative(flavours)
> rookie
I don't know about rookie. Please try again.
> banilla
'vanilla'
>>> chooseAnAlternative(['to bluff', 'true love'])
> tooblaithe
I don't know about tooblaithe. Please try again.
> to blove
'true love'
###
difflib does a very good job at trying to make sense out of the
incomprehensible.
From wsryu@fas.harvard.edu Sat Oct 13 03:14:22 2001
From: wsryu@fas.harvard.edu (William Ryu)
Date: Fri, 12 Oct 2001 22:14:22 -0400
Subject: [Tutor] Curses module?
In-Reply-To:
Message-ID: <5.1.0.14.2.20011012221118.00ae94d0@pop.fas.harvard.edu>
I was interested in learning the curses module, but when I fired up my
2.1.1 session I couldn't import it:
Python 2.1.1 (#20, Jul 20 2001, 01:19:29) [MSC 32 bit (Intel)] on win32
Type "copyright", "credits" or "license" for more information.
>>>
Traceback (most recent call last):
File "", line 1, in ?
ImportError: No module named curses
>>>
Curiously, it's not anywhere to be found in /lib. I guess I'm missing
something. Isn't the curses module supposed to be in the /lib folder, even
for the Windows distribution?
Thanks,
-willryu
From dyoo@hkn.eecs.berkeley.edu Sat Oct 13 03:51:14 2001
From: dyoo@hkn.eecs.berkeley.edu (Danny Yoo)
Date: Fri, 12 Oct 2001 19:51:14 -0700 (PDT)
Subject: [Tutor] Curses module?
In-Reply-To: <5.1.0.14.2.20011012221118.00ae94d0@pop.fas.harvard.edu>
Message-ID:
On Fri, 12 Oct 2001, William Ryu wrote:
> I was interested in learning the curses module, but when I fired up my
> 2.1.1 session I couldn't import it:
>
> Python 2.1.1 (#20, Jul 20 2001, 01:19:29) [MSC 32 bit (Intel)] on win32
> Type "copyright", "credits" or "license" for more information.
> >>>
> Traceback (most recent call last):
> File "", line 1, in ?
> ImportError: No module named curses
> >>>
>
> Curiously, it's not anywhere to be found in /lib. I guess I'm missing
> something. Isn't the curses module supposed to be in the /lib folder, even
> for the Windows distribution?
There's a 'pdcurses' library that's supposed to be simliar to the standard
Unix curses library:
http://www.mikroplan.com.pl/~mak/python/
although I'm not quite sure if this works well. Does anyone else have
experience with it? From scanning through the net, I've gotten the
impression that not many people are interested in curses programming, so
not much attention has been placed on making it work for Windows right out
of the box. And that's a shame.
There's also a library specifically for Windows that sorta provides curses
behavior called 'console', written by Fredrik Lundh:
http://w1.132.telia.com/~u13212494/efflib/console/
Good luck!
From wheelege@tsn.cc Sat Oct 13 03:54:40 2001
From: wheelege@tsn.cc (Glen Wheeler)
Date: Sat, 13 Oct 2001 12:54:40 +1000
Subject: [Tutor] Thank You! & Something for you [difflib in Python 2.1]
References:
Message-ID: <007a01c15392$67e24fe0$9aa616ca@ACE>
LOL!
>
> <...>
>
> difflib does a very good job at trying to make sense out of the
> incomprehensible.
>
Kind of like a certain person I know :) (btw nice piece on difflib)
From urnerk@qwest.net Sat Oct 13 04:03:37 2001
From: urnerk@qwest.net (Kirby Urner)
Date: Fri, 12 Oct 2001 20:03:37 -0700
Subject: [Tutor] Curses module?
In-Reply-To: <5.1.0.14.2.20011012221118.00ae94d0@pop.fas.harvard.edu>
References:
Message-ID: <4.2.0.58.20011012195907.00c55220@pop3.norton.antivirus>
At 10:14 PM 10/12/2001 -0400, William Ryu wrote:
>I was interested in learning the curses module, but when I fired up my
>2.1.1 session I couldn't import it:
Pretty much a Unix thing.
Here's a thread that might interest you:
http://groups.yahoo.com/group/python-list/message/125037
Looks like you're in for a fair amount of work if
you want Win32 curses. Easier to just dual boot
Linux IMO, which will let you play with fork module
and such as well.
Kirby
From tonycervone@netzero.net Sat Oct 13 11:38:16 2001
From: tonycervone@netzero.net (tonycervone)
Date: Sat, 13 Oct 2001 06:38:16 -0400
Subject: [Tutor] My first script within a game program
Message-ID: <000801c153d3$2c234b80$fd84f4d1@w9y5d5>
This is a multi-part message in MIME format.
------=_NextPart_000_0005_01C153B1.A3BA58E0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
I am learning Python and am trying to write a script that uses =
specific(game ) program functions for additional functionality withing =
the game play. The program is a flight sim and the two functions that I =
am trying to use are: LoadMetar() and EndSituation(). The LoadMetar() =
will call a text file, and the EndSituation() will reset the particular =
situation so that a new situation can be loaded without having to start =
the game. Here's the script so far:
from fly import *
metarFlag =3D 0
def Main(dt):
global metarFlag
if (metarFlag =3D=3D 0):
LoadMetar("Metar\InfoMetar.txt")
NoticeToUser(" loading InfoMetar Weather v1.0", 10.0)
metarFlag =3D 1
With this script placed in the program, I can successfully load the =
InfoMetar.txt when I load my first situation. The question is that if I =
want to load a new situation I need to add the EndSituation() function =
somewhere in the script in order to reset, I suspect, some flag so that =
when I start a new situation the loadMetar() function is loaded again. =
Presently, I need to restart the Game whenever I want to load a new =
situation. I hope I have provided enough clues. Unfortunately, I don't =
have any docs, thus the difficulty. tony cervone
------=_NextPart_000_0005_01C153B1.A3BA58E0
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
I am learning Python and am trying to =
write a=20
script that uses specific(game ) program functions for additional=20
functionality withing the game play. The program is a flight sim and the =
two=20
functions that I am trying to use are: LoadMetar() and EndSituation(). =
The=20
LoadMetar() will call a text file, and the EndSituation() will reset the =
particular situation so that a new situation can be loaded without =
having to=20
start the game. Here's the script so far:
from fly import *
metarFlag =3D 0
def Main(dt):
global metarFlag
if (metarFlag =3D=3D 0):
LoadMetar("Metar\InfoMetar.txt")
NoticeToUser(" loading InfoMetar Weather v1.0", 10.0)
metarFlag =3D 1
With this script placed in the program, I can =
successfully=20
load the InfoMetar.txt when I load my first situation. The question is =
that if I=20
want to load a new situation I need to add the EndSituation() function =
somewhere=20
in the script in order to reset, I suspect, some flag so that when =
I start=20
a new situation the loadMetar() function is loaded again. =
Presently, I=20
need to restart the Game whenever I want to load a new situation. =
I hope I=20
have provided enough clues. Unfortunately, I don't have any docs, thus =
the=20
difficulty. tony cervone
------=_NextPart_000_0005_01C153B1.A3BA58E0--
----------------------------------------------------
Sign Up for NetZero Platinum Today
Only $9.95 per month!
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From wheelege@tsn.cc Sat Oct 13 13:07:49 2001
From: wheelege@tsn.cc (Glen Wheeler)
Date: Sat, 13 Oct 2001 22:07:49 +1000
Subject: [Tutor] My first script within a game program
References: <000801c153d3$2c234b80$fd84f4d1@w9y5d5>
Message-ID: <00c101c153df$b8492ba0$9aa616ca@ACE>
Howdy Tony,
Next time your posting, please keep to plain text and indent your code -
thanks :)
Anywho, onto your question...
metarFlag = 0
def Main(dt):
global metarFlag
if (metarFlag == 0):
LoadMetar("Metar\InfoMetar.txt")
NoticeToUser(" loading InfoMetar Weather v1.0", 10.0)
metarFlag = 1
> With this script placed in the program, I can successfully load the
InfoMetar.txt when I load my first situation. The
> question is that if I want to load a new situation I need to add the
EndSituation() function somewhere in the script in
> order to reset, I suspect, some flag so that when I start a new situation
the loadMetar() function is loaded again.
> Presently, I need to restart the Game whenever I want to load a new
situation. I hope I have provided enough clues.
> Unfortunately, I don't have any docs, thus the difficulty. tony cervone
No docs? Try www.python.org for all the latest documentation that comes
with python. It sounds like all you need to do is add a question to the
user when they want to quit - or perhaps make the 'Reset Situation' option
in a menu somewhere? Or perhaps as a keyboard shortcut? The code should be
simple enough (sans GUI :) and all you would need to do is then call
EndSituation() once they respond.
I can't help but feel I'm missing the point here. Could you please repost
with a bit more detail?
Thanks,
Glen
From wheelege@tsn.cc Sat Oct 13 14:04:16 2001
From: wheelege@tsn.cc (Glen Wheeler)
Date: Sat, 13 Oct 2001 23:04:16 +1000
Subject: [Tutor] My first script within a game program
References: <000801c153d3$2c234b80$fd84f4d1@w9y5d5> <00c101c153df$b8492ba0$9aa616ca@ACE> <000701c153e1$f7a642e0$9e8df4d1@w9y5d5>
Message-ID: <00cf01c153e7$921cdb40$9aa616ca@ACE>
> Hi Glen.
> Sorry for the text; I am learning.
:) Also, next time you reply try using 'Reply All' - then it will be
posted to the list and me, *insert witty quote about more people being
better than one here*.
> To be more specific about my dilemma.....
> 1. Is a function like EndSituation() complete, or do I need to place
> anything after calling it, that is, to make sure that it works. If it can
> stand by itself, I think I know how to use it.
I'm not sure, it would really depend on what EndSituation exactly does.
Perhaps a few test runs could help you figure it out? Things like the
position of your plane, the landscape, things regarding the default values
for the situation would need to be preserved somewhere - but that should all
be within the function. I'd try it out.
> 2. the lack of docs referred to those that come with the game.
Ah. Probably a silly question but have you tried 'print
EndSituation.__doc__'? That could help :) If all the functions have
docstrings (.__doc__ attributes) then you can cook up a little loop that
will print out all the documentation for you. The way to do this is using
the built-in dir function which when called returns a list of all the
current object in the namespace. If that's just a whole bunch of gibberish,
then we can help you out :)
> 3. It seems that once the function LoadMetar() is called, it stays in the
> program. My dilemma is that the script in which this fuction resides is
run
> once within the program. So, it seems, that when a brand new situation is
> loaded from the program, the same script is loaded, but this time it has
to
> check for some flag that resets the LoadMetar().
I think I'm starting to understand what you mean. The problem is that the
script cannot really call itself from within itself? I don't think that
would be the behaviour of EndSituation - more likely the function halts the
current situation and restarts with a new one (perhaps a clone of the old)
but it wouldn't call the script from the beginning again.
Is there a way to ask for user input once within the program? If you can,
then a simple command from the user could invoke EndSituation and the
results could be observed directly. If not, try altering your script to
something like...
def Main(dt):
global metarFlag
if (metarFlag == 0):
LoadMetar("Metar\InfoMetar.txt")
NoticeToUser(" loading InfoMetar Weather v1.0", 10.0)
metarFlag = 1
NoticeToUser(" Ending the situation, look out!", 10.0) ## what does this
number do?
EndSituation() ## does EndSituation take any arguments?
> The good thing about trying to explain this is that it's helping me figure
> out the problem more clearly.
:) Good luck!
Glen
From rufmetal@home.com Sat Oct 13 17:24:27 2001
From: rufmetal@home.com (Chris Keelan)
Date: Sat, 13 Oct 2001 11:24:27 -0500
Subject: [Tutor] Strange modulus problem
In-Reply-To: <4.2.0.58.20011011200732.00a6ec10@pop3.norton.antivirus>
References: <4.2.0.58.20011011200732.00a6ec10@pop3.norton.antivirus>
Message-ID: <01101311242700.01473@tygesen>
On Thu, 11 Oct 2001, Kirby Urner wrote:
> This has to do with iterating over the object you're
> also modifying.
When you explain it that way, it makes perfect sense! For some reason I
didn't think that the 'for' iteration worked by index. Perhaps there was a
little gnome who took all of the objects out of a list, laid them out on a
table and picked them up, one-by-one saying "If I divide six by this, will my
remainder be zero? Nope? Well throw it out then."
;o)
>
> The code below works because it iterates over a copy
Which is how I'm gonna do this from now on.
[snip]
> This is a common programming error in Python and you're
> lucky to stumble across it in such an illuminating
> manner. It's very good to make mistakes of this kind
> -- very text book. You have a promising career as a
> Pythoneer ahead of you (pardon the fortune cookie).
You sound like my singing teacher. He told me that sometimes it was better to
be loudly wrong than to be quietly right.
Thanks for the help, Kirby.
- Chris
From rufmetal@home.com Sat Oct 13 17:36:15 2001
From: rufmetal@home.com (Chris Keelan)
Date: Sat, 13 Oct 2001 11:36:15 -0500
Subject: [Tutor] Strange modulus problem
In-Reply-To: <01101122185600.00949@tygesen>
References: <01101122185600.00949@tygesen>
Message-ID: <01101311361501.01473@tygesen>
On Thu, 11 Oct 2001, Chris Keelan wrote:
Thanks Andrew and Scott. My script now works perfectly!
- Chris
From rufmetal@home.com Sat Oct 13 18:03:04 2001
From: rufmetal@home.com (Chris Keelan)
Date: Sat, 13 Oct 2001 12:03:04 -0500
Subject: [Tutor] Now I have a variable-passing problem!
Message-ID: <01101312030400.01555@tygesen>
Thanks again to all who helped me with my list/iteration question.
Now I've made the following mess for myself:
def get_number():
rawNum=raw_input("Enter a number between 0 and 10,000: ")
try:
num_int = string.atoi(rawNum)
if (0 > num_int) or (num_int > 10000):
print 'Sorry, that number is not between 0 and 10000'
get_number()
except ValueError:
print "Try again. We need an integer between 0 and 10,000"
get_number()
return rawNum
>>Enter a number between 0 and 10,000: a
>>Try again. We need an integer between 0 and 10,000
>>Enter a number between 0 and 10,000: 50
Which, when I try to unit-test by entering a letter instead of an integer,
gives me the following.
Traceback (innermost last):
File "./6-8.py", line 127, in ?
pretty=give_me_english(list)
File "./6-8.py", line 114, in give_me_english
ones = string.atoi(digit_list[0])
ValueError: invalid literal for atoi(): a
Here's what I don't understand: get_number() is called (function A) and
assigns a raw input value to rawNum. When rawNum fails the "string.atoi"
test, the function calls itself again (function B), assinging a new value to
rawNum which does not get passed to the function A when the function B
terminates. How do I (re)write the code so that function B passes the
correct value to function A?
Should I even bother or just re-write the body of the if-test to re-prompt
without a recursive call?
- Chris
From toodles@yifan.net Sat Oct 13 17:35:23 2001
From: toodles@yifan.net (Andrew Wilkins)
Date: Sun, 14 Oct 2001 00:35:23 +0800
Subject: [Tutor] Now I have a variable-passing problem!
References: <01101312030400.01555@tygesen>
Message-ID: <001d01c15405$0fdd3710$0300a8c0@sun>
Heya Chris,
*changes order of your message*
> Should I even bother or just re-write the body of the if-test to re-prompt
> without a recursive call?
IMHO the recursive calls aren't very useful here. Here's how I'd have it
written:
(Note that you can use int('123') to convert from a string to an integer.
I'm not sure which version of Python that was introduced in, but it can
easily be changed back to string.atoi().)
def get_number():
while 1:
rawNum=raw_input("Enter a number between 0 and 10,000: ")
try:
num_int=int(rawNum)
if not (num_int<0 or num_int>10000):
return num_int
else: print 'Sorry, that number is not between 0 and
10,000'
except ValueError:
print 'Try again. We need an integer between 0 and
10,000'
>>> get_number()
Enter a number between 0 and 10,000: a
Try again. We need an integer between 0 and 10,000
Enter a number between 0 and 10,000: 50
50
HTH
Andrew
> Thanks again to all who helped me with my list/iteration question.
>
> Now I've made the following mess for myself:
>
>
> def get_number():
> rawNum=raw_input("Enter a number between 0 and 10,000: ")
>
> try:
> num_int = string.atoi(rawNum)
> if (0 > num_int) or (num_int > 10000):
> print 'Sorry, that number is not between 0 and 10000'
> get_number()
>
>
> except ValueError:
> print "Try again. We need an integer between 0 and 10,000"
> get_number()
>
> return rawNum
>
> >>Enter a number between 0 and 10,000: a
> >>Try again. We need an integer between 0 and 10,000
> >>Enter a number between 0 and 10,000: 50
>
> Which, when I try to unit-test by entering a letter instead of an integer,
> gives me the following.
>
> Traceback (innermost last):
> File "./6-8.py", line 127, in ?
> pretty=give_me_english(list)
> File "./6-8.py", line 114, in give_me_english
> ones = string.atoi(digit_list[0])
> ValueError: invalid literal for atoi(): a
>
>
> Here's what I don't understand: get_number() is called (function A) and
> assigns a raw input value to rawNum. When rawNum fails the "string.atoi"
> test, the function calls itself again (function B), assinging a new value
to
> rawNum which does not get passed to the function A when the function B
> terminates. How do I (re)write the code so that function B passes the
> correct value to function A?
>
>
> - Chris
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
From toodles@yifan.net Sat Oct 13 17:35:23 2001
From: toodles@yifan.net (Andrew Wilkins)
Date: Sun, 14 Oct 2001 00:35:23 +0800
Subject: [Tutor] Now I have a variable-passing problem!
References: <01101312030400.01555@tygesen>
Message-ID: <001d01c15405$0fdd3710$0300a8c0@sun>
Heya Chris,
*changes order of your message*
> Should I even bother or just re-write the body of the if-test to re-prompt
> without a recursive call?
IMHO the recursive calls aren't very useful here. Here's how I'd have it
written:
(Note that you can use int('123') to convert from a string to an integer.
I'm not sure which version of Python that was introduced in, but it can
easily be changed back to string.atoi().)
def get_number():
while 1:
rawNum=raw_input("Enter a number between 0 and 10,000: ")
try:
num_int=int(rawNum)
if not (num_int<0 or num_int>10000):
return num_int
else: print 'Sorry, that number is not between 0 and
10,000'
except ValueError:
print 'Try again. We need an integer between 0 and
10,000'
>>> get_number()
Enter a number between 0 and 10,000: a
Try again. We need an integer between 0 and 10,000
Enter a number between 0 and 10,000: 50
50
HTH
Andrew
> Thanks again to all who helped me with my list/iteration question.
>
> Now I've made the following mess for myself:
>
>
> def get_number():
> rawNum=raw_input("Enter a number between 0 and 10,000: ")
>
> try:
> num_int = string.atoi(rawNum)
> if (0 > num_int) or (num_int > 10000):
> print 'Sorry, that number is not between 0 and 10000'
> get_number()
>
>
> except ValueError:
> print "Try again. We need an integer between 0 and 10,000"
> get_number()
>
> return rawNum
>
> >>Enter a number between 0 and 10,000: a
> >>Try again. We need an integer between 0 and 10,000
> >>Enter a number between 0 and 10,000: 50
>
> Which, when I try to unit-test by entering a letter instead of an integer,
> gives me the following.
>
> Traceback (innermost last):
> File "./6-8.py", line 127, in ?
> pretty=give_me_english(list)
> File "./6-8.py", line 114, in give_me_english
> ones = string.atoi(digit_list[0])
> ValueError: invalid literal for atoi(): a
>
>
> Here's what I don't understand: get_number() is called (function A) and
> assigns a raw input value to rawNum. When rawNum fails the "string.atoi"
> test, the function calls itself again (function B), assinging a new value
to
> rawNum which does not get passed to the function A when the function B
> terminates. How do I (re)write the code so that function B passes the
> correct value to function A?
>
>
> - Chris
>
> _______________________________________________
> Tutor maillist - Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
>
From arcege@speakeasy.net Sat Oct 13 17:39:33 2001
From: arcege@speakeasy.net (Michael P. Reilly)
Date: Sat, 13 Oct 2001 12:39:33 -0400
Subject: [Tutor] Strange modulus problem
In-Reply-To: <01101311242700.01473@tygesen>; from rufmetal@home.com on Sat, Oct 13, 2001 at 11:24:27AM -0500
References: <4.2.0.58.20011011200732.00a6ec10@pop3.norton.antivirus> <01101311242700.01473@tygesen>
Message-ID: <20011013123933.C982@speakeasy.net>
On Sat, Oct 13, 2001 at 11:24:27AM -0500, Chris Keelan wrote:
> On Thu, 11 Oct 2001, Kirby Urner wrote:
>
> > This has to do with iterating over the object you're
> > also modifying.
>
> When you explain it that way, it makes perfect sense! For some reason I
> didn't think that the 'for' iteration worked by index. Perhaps there was a
> little gnome who took all of the objects out of a list, laid them out on a
> table and picked them up, one-by-one saying "If I divide six by this, will my
> remainder be zero? Nope? Well throw it out then."
Also, instead of removing items, you can append items to a new list:
m = range(100)
l = []
for i in m:
if (i % 13) == 0:
l.append( i )
print l
[0, 13, 26, 39, 52, 65, 78, 91]
Then there is no need to create a copy of the list, which could be
expensive if the list is large, and not removing items from a list,
which you can see is problematic.
-Arcege
--
+----------------------------------+-----------------------------------+
| Michael P. Reilly | arcege@speakeasy.net |
From wheelege@tsn.cc Sun Oct 14 03:20:00 2001
From: wheelege@tsn.cc (Glen Wheeler)
Date: Sun, 14 Oct 2001 12:20:00 +1000
Subject: [Tutor] Now I have a variable-passing problem!
References: <01101312030400.01555@tygesen>
Message-ID: <006101c15456$ba4529a0$c1a616ca@ACE>
Hi,
Since I couldn't see anything written by Andrew to show an implementation
method that uses recursion, I thought I'd chuck one in. True, it's better
using a loop but... some people just like recursion :)
> Now I've made the following mess for myself:
heh :)
> def get_number():
> rawNum=raw_input("Enter a number between 0 and 10,000: ")
>
> try:
> num_int = string.atoi(rawNum)
> if (0 > num_int) or (num_int > 10000):
> print 'Sorry, that number is not between 0 and 10000'
> rawNum = get_number() # lest the value is lost in the wicked
maze of recursion :)
>
>
> except ValueError:
> print "Try again. We need an integer between 0 and 10,000"
> get_number()
>
> return rawNum
>
> <...>
>
> Here's what I don't understand: get_number() is called (function A) and
> assigns a raw input value to rawNum. When rawNum fails the "string.atoi"
> test, the function calls itself again (function B), assinging a new value
to
> rawNum which does not get passed to the function A when the function B
> terminates. How do I (re)write the code so that function B passes the
> correct value to function A?
>
Your code looks all well and good, but has a pretty major problem. When
you recursively call get_number you aren't storing the value - something
like 'result = get_number()' is needed. When you do this, you also need to
declare result (again, simple as 'result = None') and modify the return
statement. So, only really one change but the new incarnation would be...
def get_number():
rawNum=raw_input("Enter a number between 0 and 10,000: ")
try:
result = None # don't want an unbound var error...
num_int = int(rawNum)
if (0 > num_int) or (num_int > 10000):
print 'Sorry, that number is not between 0 and 10000'
result = get_number() # lest the value is lost in the wicked
maze of recursion :)
except ValueError:
print "Try again. We need an integer between 0 and 10,000"
result = get_number() # ditto
if result:
return result
else:
return rawNum
> Should I even bother or just re-write the body of the if-test to re-prompt
> without a recursive call?
>
It's not too much trouble to correctly recursify it, esp if you've already
built the function.
Anywho, have fun :)
Glen
From Keila - Curitiba - Pr"
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abaixo. GARANTO SER SUI-GENERIS - CLIQUE ABAIXO:
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- Podes falar comigo, direto dela. Brevemente uma Carta Aberta.
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From shalehperry@home.com Sun Oct 14 03:46:42 2001
From: shalehperry@home.com (Sean 'Shaleh' Perry)
Date: Sat, 13 Oct 2001 19:46:42 -0700 (PDT)
Subject: [Tutor] Now I have a variable-passing problem!
In-Reply-To: <006101c15456$ba4529a0$c1a616ca@ACE>
Message-ID:
>> Should I even bother or just re-write the body of the if-test to re-prompt
>> without a recursive call?
>>
>
> It's not too much trouble to correctly recursify it, esp if you've already
> built the function.
>
the problem with recursion is the case where the user (or whatever) just keeps
sending bad input. Then the recursion just gets deeper and deeper, python will
eventually hiccup or segfault. Also recursion is more expensive than the loop,
especially if the user/input has many incorrect entries.
From wheelege@tsn.cc Sun Oct 14 05:31:39 2001
From: wheelege@tsn.cc (Glen Wheeler)
Date: Sun, 14 Oct 2001 14:31:39 +1000
Subject: [Tutor] Now I have a variable-passing problem!
References:
Message-ID: <008b01c15469$1e9ba2a0$c1a616ca@ACE>
> >> Should I even bother or just re-write the body of the if-test to
re-prompt
> >> without a recursive call?
> >>
> >
> > It's not too much trouble to correctly recursify it, esp if you've
already
> > built the function.
> >
>
> the problem with recursion is the case where the user (or whatever) just
keeps
> sending bad input. Then the recursion just gets deeper and deeper, python
will
> eventually hiccup or segfault. Also recursion is more expensive than the
loop,
> especially if the user/input has many incorrect entries.
>
Right...I was only showing how to do it the recursive way for academic
purposes - 'If we lived in this alternate universe where loops didn't exist,
how would we implement it?' :)
From urnerk@qwest.net Sun Oct 14 05:56:01 2001
From: urnerk@qwest.net (Kirby Urner)
Date: Sat, 13 Oct 2001 21:56:01 -0700
Subject: [Tutor] Intro to CS (boolean.py)
In-Reply-To: <4.2.0.58.20011013090449.00c02990@pop3.norton.antivirus>
References:
Message-ID: <4.2.0.58.20011013213544.00c4f5d0@pop3.norton.antivirus>
Here's a simple boolean algebra module, for which
"useless Python" I'll no doubt find many more capable
versions (haven't checked yet).
Still, I like this one because it includes a broad
range of Python concepts in not-too-difficult form,
namely:
* a simple class: the Bool class does little more than
override the behavior of __invert__ for integers, so
instead of getting two's complement, I get the logical
negation, i.e. I say '~a' instead of 'not a'.
* a regular expression: really basic, but used to find
all occurances of a single letter variable, and replace
it with ~variable. This version only allows up to four
variables a-d.
* plenty of string manipulation, which is the nuts and
bolts of a lot of programming
* an example of eval() with a local namespace
Here's how it looks, used in shell mode:
>>> reload(boolean)
>>> boolean.truth(1,'~a')
a | ~a
==|===
0 | 1
1 | 0
>>> expr = "(a & ~b) | c"
>>> boolean.truth(3,expr)
a b c | (a & ~b) | c
======|=============
0 0 0 | 0
0 0 1 | 1
0 1 0 | 0
0 1 1 | 1
1 0 0 | 1
1 0 1 | 1
1 1 0 | 0
1 1 1 | 1
>>> newexpr = boolean.demorgan(expr)
>>> newexpr
'~(((~a) | ~(~b)) & (~c))'
>>> boolean.truth(3,newexpr)
a b c | ~(((~a) | ~(~b)) & (~c))
======|=========================
0 0 0 | 0
0 0 1 | 1
0 1 0 | 0
0 1 1 | 1
1 0 0 | 1
1 0 1 | 1
1 1 0 | 0
1 1 1 | 1
As an intro to computer science module, it's got some
other key stuff too, in addition to exercising the above
features of Python (which features are characteristic
of many other languages).
It's got decimal to binary conversion...
>>> from boolean import bin
>>> bin(10)
'1010'
>>> bin(100)
'1100100'
>>> bin(3242034)
'1100010111100000110010'
And it's got this DeMorgan's equivalence relation, whereby
you can express the same logical expression in two different
ways. CS students know what I'm talking about.
That being said, I'm sure the code could be enchanced/improved,
features added and so on (I'm working on an improvement or
two right now).
So, have at it...
Kirby
=====
"""
Simple boolean algebra module by
Kirby Urner, Oct 13, 2001
"""
from string import replace, center
from re import sub
class Bool:
"""
Intialize w/ 1 or 0: a,b = Bool(1), Bool(0)
Example expressions: a&b, a|b, ~a (note: ~ for negation)
returns a Bool
"""
def __init__(self,val):
if not (val==0 or val==1):
raise ValueError,"Must be 1 or 0"
self.value = val
def __invert__(self):
return Bool(not self.value)
def __and__(self,other):
return Bool(self.value & other.value)
def __or__(self,other):
return Bool(self.value | other.value)
def __repr__(self):
return repr(self.value)
def demorgan(expr):
"""
Swap & with |, negate args, negate expression
-- should have same truth table as original
"""
def negate(matchobj):
t = matchobj.group(0)
return '(~%s)' % t
expr = replace(expr,'&','@')
expr = replace(expr,'|','&')
expr = replace(expr,'@','|')
expr = sub('[a-d]',negate,expr)
return "~("+expr+")"
def bin(n):
result = ''
while 1:
result = str(n%2)+result
n = n//2
if not n: break
return result
def truth(n,expr):
"""
Generates truth table for n=1-4 variables a-d,
for the passed boolean expression expr
"""
truth_table = []
locals = {}
padding = n*'0'
for i in range(2**n):
digits = (padding + bin(i))[-n:]
truth_table.append(tuple(digits))
print
print " "+("%s "*n) % tuple('abcd')[:n] + "| " + expr
print " "+"=="*n + "|=" + "="*len(expr)
for row in truth_table:
for i in range(n):
locals['abcd'[i]]=Bool(int(row[i]))
print " "+("%s "*n) % row + "| " + \
center(str(eval(expr,locals)),len(expr))
print
=====
From rufmetal@home.com Sun Oct 14 07:09:03 2001
From: rufmetal@home.com (Chris Keelan)
Date: Sun, 14 Oct 2001 01:09:03 -0500
Subject: [Tutor] Now I have a variable-passing problem!
In-Reply-To: <006101c15456$ba4529a0$c1a616ca@ACE>
References: <01101312030400.01555@tygesen> <006101c15456$ba4529a0$c1a616ca@ACE>
Message-ID: <01101401090301.01744@tygesen>
On Sat, 13 Oct 2001, Glen Wheeler wrote:
> Your code looks all well and good, but has a pretty major problem. When
> you recursively call get_number you aren't storing the value - something
> like 'result = get_number()' is needed.
That's what I thought. I also understand why recursion is a potentially
BadThing[TM], at least in this situation.
>When you do this, you also need to
> declare result (again, simple as 'result = None') and modify the return
> statement. So, only really one change but the new incarnation would be...
>
> def get_number():
> rawNum=raw_input("Enter a number between 0 and 10,000: ")
>
> try:
> result = None # don't want an unbound var error...
> num_int = int(rawNum)
> if (0 > num_int) or (num_int > 10000):
> print 'Sorry, that number is not between 0 and 10000'
> result = get_number() # lest the value is lost in the wicked
> maze of recursion :)
>
> except ValueError:
> print "Try again. We need an integer between 0 and 10,000"
> result = get_number() # ditto
>
> if result:
> return result
> else:
> return rawNum
>
> > Should I even bother or just re-write the body of the if-test to
> > re-prompt without a recursive call?
>
> It's not too much trouble to correctly recursify it, esp if you've
> already built the function.
This is good advice, but I think I agree (as you do) with Sean and Andrew's
"loop" approach, which is the one I'm going to use.
>
> Anywho, have fun :)
When I look up "fun" in the dictionary, the third entry says "see `Python' ",
heh!
Thanks again gang. If anyone is ever in the Toronto area, I'm buying the beer!
- Chris
From kaya4321@yahoo.com Sun Oct 14 10:27:21 2001
From: kaya4321@yahoo.com (necati kaya)
Date: Sun, 14 Oct 2001 02:27:21 -0700 (PDT)
Subject: [Tutor] seed & random !?
Message-ID: <20011014092721.55396.qmail@web9207.mail.yahoo.com>
Hi,
I am trying to generate different new_list randomly in
each step of the loop from original_list, but I can
not. As the example;
original_list=['1','2','3','4'] and my program produce
those new_lists randomly, but
['4', '2', '3', '1'] ==>
['1', '4', '2', '3'] Both are same
['4', '2', '3', '1'] ==>
['3', '2', '1', '4']
['2', '4', '3', '1']
I tried to use seed function, but it gave me all the
same results. Do you have any suggestion to have
different new_list which is generated from
original_list in every step.
Regards,
umit
Here is my code:
from random import Random
import random
original_list=['1','2','3','4']
for j in range(0, 5):
temp_list = original_list[:]
new_list=[]
for i in range(0, len(original_list)):
# random.seed()
#??????????????
choosen_item = random.choice(temp_list)
new_list.append(choosen_item)
temp_list.remove(choosen_item)
print new_list
print
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From samirdpatel@hotmail.com Sun Oct 14 10:28:55 2001
From: samirdpatel@hotmail.com (Samir Patel)
Date: Sun, 14 Oct 2001 09:28:55
Subject: [Tutor] finding title tag in a link tag ??
Message-ID:
hi,
i am trying to save a list of links present a url which is given through command line.i am doing this to a certain depth and saving all this links in a universal list.
now my problem is that i want to get the titles present in that Achor tag e.g
<a href = "url" title = "i want this">or this</a>
so how can i get that and store that with respective particular link.
following is the code which i have written and want to add adove stuff to it.....
import re