[Tutor] extracting a column from many files

[Kent Johnson]

On Thu, Feb 19, 2009 at 5:41 AM, Bala subramanian
<bala.biophysics at gmail.com> wrote:
> Dear friends,
>
> I want to extract certain 6 different columns from a many files and write it
> to 6 separate output files. I took some help from the following link
>
> http://mail.python.org/pipermail/tutor/2004-November/033475.html
>
> to write one column from many input files to a particular output file. Since
> i have to extract 6 such columns, i wanted to loop the output file writing
> part.

Do you want the resulting files to have a single column, or one column
per input file? The mail you cite has one column per file.

> This block of the script is shown in bold below. I see some odd output
> file names.

You are using the string representation of the values as the file
name! What do you want to call the files?

>  Kindly suggest me i ) how best or should i do this loop part
> ii) explanation of the working row=map(None,*value) below which i adopted
> from the above tutor-mail list link.

Please clarify what you want to do first.
Kent

>
> Thanks in advance,
> Bala
>
>  #!/usr/bin/env python
> from sys import argv
> lst_files=argv[1:]
>
> sh=[];st=[];sta=[];buc=[];pro=[];ope=[]
>
> def extract(fname):
>     A=[];B=[];C=[];D=[];E=[];F=[]
>     data=open(fname).readlines()
>     for number, line in enumerate(data):
>         if "  Duplex" and " Shear" in line:
>             number=number+3
>         for x in range(0,8):
>                 new=data[number]
>                 A.append(new[19:26])
>                 B.append(new[27:34])
>                 C.append(new[37:42])
>                 D.append(new[44:54])
>                 E.append(new[56:63])
>                 F.append(new[69:75])
>                 number = number + 1
>     sh.append(A)
>     st.append(B)
>     sta.append(C)
>     buc.append(D)
>     pro.append(E)
>     ope.append(F)
>
> for x in lst_files:
>           extract(x)
>
> list=[sh,st,sta,buc,pro,ope]
> for value in list:
>     row=map(None,*value)
>     out=open(str(value) + '.txt','w')
>     for num in row:
>           out.write('\t'.join(num))
>           out.write('\n')
>     out.close()
>
>
>
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