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

[Isaac]

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?
>> > _______________________________________________
>> > Baypiggies mailing list
>> > Baypiggies at python.org
>> > To change your subscription options or unsubscribe:
>> > http://mail.python.org/mailman/listinfo/baypiggies
>>
>>
>>
>> _______________________________________________
>> Baypiggies mailing list
>> Baypiggies at python.org
>> To change your subscription options or unsubscribe:
>> http://mail.python.org/mailman/listinfo/baypiggies
>>
>
>
> _______________________________________________
> Baypiggies mailing list
> Baypiggies at python.org
> To change your subscription options or unsubscribe:
> http://mail.python.org/mailman/listinfo/baypiggies
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/baypiggies/attachments/20080616/85ec5d4d/attachment.htm>