[Tutor] Tutor Digest, Vol 71, Issue 78
Aneftaoratos Aneftaoratos
aneftaoratos at gmail.com
Sun Jan 31 01:11:27 CET 2010
#1 1.1 Write a Python program with a loop that prints out a sequence
of numbers as follows:151311...31-1
A simple approach with a for loop:
def MyRange(start, end, step):
for n in range(start, end, step):
if n == 0:
print -1
break
else:
print n
return
#call the function
MyRange(151311, -1, -31)
Hope that helps!
2010/1/31 <tutor-request at python.org>:
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> Today's Topics:
>
> 1. Re: can any one help (invincible patriot)
> 2. Re: can any one help (Grigor Kolev)
> 3. please help me (invincible patriot)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 30 Jan 2010 23:24:18 +0000
> From: invincible patriot <invincible_patriot at hotmail.com>
> To: <grigor.kolev at gmail.com>
> Cc: tutor at python.org
> Subject: Re: [Tutor] can any one help
> Message-ID: <COL107-W13C745249B64F8355E768AE25A0 at phx.gbl>
> Content-Type: text/plain; charset="windows-1251"
>
>
> ???? didnt got what u replied
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> Subject: Re: [Tutor] can any one help
> From: grigor.kolev at gmail.com
> To: invincible_patriot at hotmail.com
> CC: anand.shashwat at gmail.com; tutor at python.org
> Date: Sun, 31 Jan 2010 01:21:15 +0200
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> ? 22:49 +0000 ?? 30.01.2010 (??), invincible patriot ??????:
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> ya definately, just give me the hint
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> i made a prog for the first one but it when ran, saying RESTART in active shell
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> def fibn(n):
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> a,b=15,2
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> while a>n:
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> print a,
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> a,b=a,a+b
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> fibn(-1)
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> whatz rong in this prog that the error is saying no break point
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> thanks
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> From: anand.shashwat at gmail.com
>
> Date: Sun, 31 Jan 2010 04:16:40 +0530
>
> Subject: Re: [Tutor] can any one help
>
> To: invincible_patriot at hotmail.com
>
> CC: tutor at python.org
>
>
>
> I got the question. I just gave you hints, so as you can try yourself. Also please use 'Reply all'
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> On Sun, Jan 31, 2010 at 4:08 AM, invincible patriot <invincible_patriot at hotmail.com> wrote:
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> I want to use WHILE LOOP in the first one and in the second question we need to take a string 'foobar' and then we should make the prog to get the following out put
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> let me tel u the exact question
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> Write a small Python program that generates the list of all pairs of characters c and
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> its doubling 2 c, where c moves through all the letters of the string "foobar" and prints it out.
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> The result will look like:
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> [(?f?, ?ff?), (?o?, ?oo?), (?o?, ?oo?), (?b?, ?bb?), (?a?, ?aa?), (?r?, ?rr?)]
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> thatz the exact 2nd question
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> also let me know aboutthe first one
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> thanks allot
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> From: anand.shashwat at gmail.com
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> Date: Sun, 31 Jan 2010 04:05:09 +0530
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> Subject: Re: [Tutor] can any one help
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> To: invincible_patriot at hotmail.com
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> CC: tutor at python.org
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> Tips:
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> 1.
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> range can be stepped down in reverse order
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> ex ->
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> >>> range(10, 1, -2)
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> [10, 8, 6, 4, 2]
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> 2.
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> you can directly get chars of string.
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> ex ->
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> >>> [i for i in 'foobar']
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> ['f', 'o', 'o', 'b', 'a', 'r']
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> also
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> >>> 2 * 'f'
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> 'ff'
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> On Sun, Jan 31, 2010 at 3:56 AM, Shashwat Anand <anand.shashwat at gmail.com> wrote:
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> seems like homework ;)
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> Can you paste your approach here ?
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> On Sun, Jan 31, 2010 at 3:03 AM, invincible patriot <invincible_patriot at hotmail.com> wrote:
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> hi
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> i am stuck in few tasks can some one help me in that
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> here are first few tasks
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> 1
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> how can i print the following series, using a loop
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> 15
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> 13
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> -1
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> ========
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> 2
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> Write a small Python program that generates the list of all pairs of characters c and
>
>
>
>
>
>
>
>
> its doubling 2 c, where c moves through all the letters of the string "foobar" and prints it out.
>
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> The result will look like:
>
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> [(?f?, ?ff?), (?o?, ?oo?), (?o?, ?oo?), (?b?, ?bb?), (?a?, ?aa?), (?r?, ?rr?)]
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> please help me out in these two tasks
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>
>
>
>
>
> def fibn(n):
>
> a,b=15,2
>
> while a>n:
>
> print a, # it is same like print a, a, b = a, a+b You can not print this. SyntaxError: invalid syntax
>
> a,b=a,a+b
>
> fibn(-1)
>
>
>
>
> --
>
> Grigor Kolev <grigor.kolev at gmail.com>
>
>
>
> _________________________________________________________________
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> ------------------------------
>
> Message: 2
> Date: Sun, 31 Jan 2010 01:40:41 +0200
> From: Grigor Kolev <grigor.kolev at gmail.com>
> To: invincible patriot <invincible_patriot at hotmail.com>
> Cc: tutor at python.org
> Subject: Re: [Tutor] can any one help
> Message-ID: <1264894841.6587.39.camel at dedal-laptop>
> Content-Type: text/plain
>
> Excuse me but I have question too.
> Why when i write this function in python shell not work says
> SyntaxError: invalid syntax
> but when I use IDLE make endless loop
> Sorry I also teach Python.
>> def fibn(n):
>> a,b=15,2
>> while a>n:
>> print a, # it is same like print a, a, b = a, a+b
>> You can not print this. SyntaxError: invalid syntax
>> a,b=a,a+b
>> fibn(-1)
> --
> Grigor Kolev <grigor.kolev at gmail.com>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 30 Jan 2010 23:46:30 +0000
> From: invincible patriot <invincible_patriot at hotmail.com>
> To: <tutor at python.org>
> Subject: [Tutor] please help me
> Message-ID: <COL107-W365777C651FE3FFF81459CE25A0 at phx.gbl>
> Content-Type: text/plain; charset="windows-1252"
>
>
> hii am stuck in these questions can someone please help me in solving and writing programme for these tasks
> please help me
>
>
>
>
> 1 1.1 Write a Python program with a loop that prints out a sequence of numbers as follows:151311...31-1
>
> 1.2 Write a small Python program that generates the list of all pairs of characters c andits doubling 2 c, where c moves through all the letters of the string "foobar" and prints it out.The result will look like:[(?f?, ?ff?), (?o?, ?oo?), (?o?, ?oo?), (?b?, ?bb?), (?a?, ?aa?), (?r?, ?rr?)]Hint: use list comprehensions.
> 1.3 Write a small Python program that
> 1. prints out the length of the string?taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu?
> 2. prints out how many different characters this string contains
> 3. replaces all the non-?t? characters in above string with dots ?.?. So, if the word were?tattoo?, it would print ?t.tt..?.Hints:
> (a) use a function to t-ify the string
> (b) there are various ways to construct the string, either using the join method or by runninga loop accumulating substrings.
> (c) check also out what happens if you apply the conversion list(s) to a string s.
> 2 2.1 Write a function count char(s, c) that takes a string s, and a character c and returnshow often the character c appears in the string.For example count_char("tattoo", "t") should return 3.
>
> 2.2 Write a Python function char_freqency(s)that returns a dictionary which, for eachcharacter of s as a key, stores as value how often this character appears.For example, char_frequency("tattoo") could return {?a?: 1, ?t?: 3, ?o?: 2} (the order ofkey:value pairs does not matter here).
> Hint: Consider using the function count_char defined in 2.1.
> 2.3 Write a program that translates a given string (of arbitrary length) of DNA bases intothe RNA strand that it will produce. For this, research which DNA bases correspond to RNA basesand create a translation table (not an if...else clause!) in the Python program. [4 marks]
>
>
> 3
> 3.1 consider the following list of base sequences:ACGTACCTTACTTACCATATCGTACCTCTTACTCATThe task consists of writing a Python program that performs a simple alignment algorithm onthese two strings and prints out this alignment in a suitable readable form. Give a brief commentexplaining the output format.Hints:1. Matching means the following: for a given sequence to be matched, your program should denotewhich bases correspond to bases in the reference sequence and which do not; in addition, markgaps where the reference sequence contains bases which are not present in the sample sequence.For a given sample sequence, your matching algorithm will attempt to match as many basesas possible to those of the reference sequence.2. This is a difficult assignment. Do not attempt it before you have solved the others.3. For this purpose, you are allowed to research and implement publicly documented versions ofthe Needleman-Wunsch algorithm or similar algorithms (however, make sure that you r
> efer-ence them properly!). Also make sure that your program prints out the matches/mismatchesbetween the sequences. You should demonstrate at least two different alignments by usingdifferent gap penalties.Instead of following this hint, you can develop an alternative solution to the matching problem,e.g. based on the Levenshtein distance.
>
>
> please help me
> _________________________________________________________________
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