[Tutor] Fwd: swapping lines between files

[Kent Johnson]

Forwarding to the list


---------- Forwarded message ----------
From: Bala subramanian <bala.biophysics at gmail.com>
Date: Tue, Mar 24, 2009 at 11:23 AM
Subject: Re: [Tutor] swapping lines between files
To: Kent Johnson <kent37 at tds.net>


Hai Kent,

Thank you. I tried the same zip with a list and a file, instead of
just two files. It works fine. But now i am stuck in overwriting the
input file with value.

What i want to do ?
I have 3 files
file 1         file2         file3
1    20.22     22  22.22       56  66.77
2    21.24     20  34.56       44  66.55
3    33.33     22  35.77       22  45.66
Now i have a list

all =[ [5,10,13], [44,56,77], [55,67,78]]

file 1              file 2              file 3
5     20.22      44  22.22       55  66.77
10    21.24     56  34.56       67  66.55
13    33.33     77  35.77       78  45.66

I am replacing the first position in file with the values in the list.

The following worked for me,

rmsd=argv[1:]
for n in range(3):
       infile=open(rmsd[n])
       for x, y in zip(all[n],infile):
           yitem=y.split()
           yitem[0]=str(x)
           print yitem

But now i simply want to overwrite the input files. I am stuck here
because when i create a filelist like the following,

file_list=FileInput(rmsd,inplace=1)
print file_list
<fileinput.FileInput instance at 0x85bdb6c>

Now file_list is not a list to loop but a fileinput object, so i am
stuck in looping this and my list all simultaneously.

Bala

On Mon, Mar 23, 2009 at 6:42 PM, Kent Johnson <kent37 at tds.net> wrote:
>
> On Mon, Mar 23, 2009 at 12:39 PM, Bala subramanian
> <bala.biophysics at gmail.com> wrote:
> > Dear Friends,
> >
> > Thanks for your replies for my previous mail.
> >
> > I have two files as follows.
> >
> > file 1         file2
> > 200           1         3.55
> > 210           2         4.55
> > 242           3         1.22
> > 248           4         3.10
> > 256            5        1.11
> >
> > Now i have to replace 1,2,3,4,5 in file 2 with 200,210,242,248,256 in file1.
> > Simply replacing position 1 in file2 with values in file1. Can i do it with
> > zip function, if yes how to do it. Here both files contain same number of
> > lines.
>
> You can use zip() to combine the lines of the files. itertools.izip()
> might be a better choice because it doesn't read the entire file at
> once. Something like this (untested):
>
> from itertools import izip
> file2 = open(...)
> out = open(..., 'w') # output file
> for line1, line2 in izip(file1, file2):
>  # now create a line that merges the two and write it
>  line1 = line1.strip()  # remove newline
>  line2items = line2.split()
>  line2items[0] = line1
>  newLine = '\t'.join(line2items)
>  out.write(newLine)
>  out.write('\n')
> out.close()
>
> Kent