[Tutor] Accessing columns of a CSV file

[Erik H.]

Also notice that in time_list you use %H:%M format, while in your rows
the format is %H:%M:%S. Simple string comparison won't work, unless
you add those seconds to your time_list.

Regards,

Erik


On Wed, Nov 17, 2010 at 2:59 PM, Hanlie Pretorius
<hanlie.pretorius at gmail.com> wrote:
> Hi,
>
> I'm reading a CSV file and I want to test the contents of its second
> column before I write it to an output file:
>
>>>> import csv
>>>> time_list=['00:00', '03:00', '06:00','09:00','12:00','15:00','18:00','21:00']
>>>> readfile='C8R004_flow.csv'
>>>> in_text=open(readfile,'rb')
>>>> cr=csv.reader(in_text)
>>>> cr
> <_csv.reader object at 0x7f4dfc3b2360>
>>>> for row in cr:
> ...     print row
> ['2005/01/31', '21:00:00', '26.508']
> ['2005/01/31', '21:12:00', '26.508']
> ['2005/01/31', '21:24:00', '26.508']
> ['2005/01/31', '21:36:00', '26.508']
> ['2005/01/31', '21:48:00', '26.508']
> ['2005/01/31', '22:00:00', '26.508']
> ['2005/01/31', '22:12:00', '26.508']
> ['2005/01/31', '22:24:00', '26.508']
> ['2005/01/31', '22:36:00', '26.508']
> ['2005/01/31', '22:48:00', '26.508']
> ['2005/01/31', '23:00:00', '26.508']
> ['2005/01/31', '23:12:00', '26.508']
> ['2005/01/31', '23:24:00', '26.508']
> ['2005/01/31', '23:36:00', '26.508']
> ['2005/01/31', '23:48:00', '26.508']
>>>>
>
> I would like to test the values in the second column to see if they're
> in the list I named time_list and, if so, write the whole row to an
> output file.
>
> The problem is that I don't know how to access the second column of
> values. I tried the direct route:
>>>> for row in cr:
> ...     print cr[1]
> ...
>>>>
>
> and I've tried to convert the csv.reader object into a list:
>
> [code]
>>>> file_rows=[]
>>>> for row in cr:
> ...     file_rows.append(row)
> ...
>>>> file_rows
> []
> [/code]
>
> which clearly doesn't work.
>
> Can someone perhaps suggest a method to access the value in the second
> column of each row so that I can test it against the time_list?
>
> Thanks
> Hanlie
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