[Baypiggies] Fw: Re: Preserving integers when loading a file into a list

[Seth Friedman]

thanks, i hadn't mapped that concept onto what i saw yet.

On Mon, Jun 16, 2008 at 12:22 AM, Isaac <hyperneato at gmail.com> wrote:

> it is a list comprehension.
>
> http://docs.python.org/tut/node7.html#SECTION007140000000000000000
>
>
> On Mon, Jun 16, 2008 at 7:18 AM, Seth Friedman <sfseth at gmail.com> wrote:
>
>> ok i'm a python newb, but can someone answer the following syntax question
>> that's been bugging me:
>>
>> the following line
>>
>>       temp = [try_int_convert(x)  for x in line.strip().split('        ')]
>>
>> what is temp = [  ...whatever ... ]  doing?
>>
>> i'm used to [ .. ] as array syntax, clearly i'm missing some capability
>> here.    what does python code enclosed in square brackets do?    i could
>> guess but seems like i might get a stronger answer from the experts.
>>
>> ~seth
>>
>>
>>
>> On Mon, Jun 16, 2008 at 12:08 AM, Al Nevarez <anevare2 at yahoo.com> wrote:
>>
>>> Thanks for the tips everyone.
>>> I'm running an older version of Python.. but the following combination of
>>> your suggestions worked just fine in yielding a list of lists with integers
>>> and strings preserved.
>>>
>>> my_data[]
>>> data_file='datasource.txt'
>>>
>>> def try_int_convert(sval):
>>>    try:
>>>        return int(sval)
>>>    except ValueError:
>>>        return sval
>>>
>>> for line in open(data_file):
>>>       temp = [try_int_convert(x)  for x in line.strip().split('
>>>  ')]
>>>       my_data.append(temp)
>>>
>>>
>>> Works fine when the value is blank in the original tab delimited file too
>>> (must be a tab there of course).  Seems to work perfectly, but does anybody
>>> spot any issue?
>>>
>>>
>>> Al
>>>
>>>
>>>
>>> --- On Sun, 6/15/08, Brent Pedersen <bpederse at gmail.com> wrote:
>>>
>>> > From: Brent Pedersen <bpederse at gmail.com>
>>> > Subject: Re: [Baypiggies] Preserving integers when loading a file into
>>> a list
>>> > To: "Jason Culverhouse" <jason at mischievous.org>
>>> > Cc: baypiggies at python.org
>>> > Date: Sunday, June 15, 2008, 1:46 PM
>>> > On Sun, Jun 15, 2008 at 12:31 PM, Jason Culverhouse
>>> > <jason at mischievous.org> wrote:
>>> > > not x.isdigit() and x or int(x) is going to fail for
>>> > empty string... ''
>>> > >        not False and '' or int('')
>>> > <-value error since
>>> > >
>>> > > You could combine Adam's try_int_convert
>>> > >
>>> > > import csv
>>> > > import functools
>>> > > import sys
>>> > >
>>> > > i = functools.partial(map, try_int_convert) # maybe
>>> > convert a list to int
>>> > > t = functools.partial(tuple) # convert to tuple, not
>>> > sure if you need the in
>>> > > tuples
>>> > >
>>> > > #Read a TSV file from stdin and convert
>>> > > [t(i(line)) for line in csv.reader(sys.stdin,
>>> > dialect='excel-tab')]
>>> > >
>>> > > Jason
>>> >
>>> > good point. out of curiosity, how is t =
>>> > functools.partial(tuple),
>>> > then using t() different from using tuple() directly?
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>>
>>
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