[Tutor] how to select a column from all files in one directory?

[kumar s]

Dear Kent and John, 
  thank you very much for your solutions. It is
working, however, there is a problem in printing the
output in a proper way:

 
>>> path = "C:\\Documents and Settings\\data\\"
>>> files = os.listdir(path)
>>> out = file('output.txt','w')
>>> for inFile in files:
	f = file(path + inFile,'r')
	for line in f:
		b = line.split('\t')
		if len(b)>=3:
			out1.write(b[3] + '\n' )
	f.close()



Here the output files has the 4th column from all the
files in one single column. 

I wanted to have 40 columns (4th column of 40 files)
rather instead of one column. 

I do not no how to ask the loop to print the contents
of 4th column in second file after a tab. 

file1     file2     file3    file4    file5
1.4        34.5      34.2     567.3    344.2
34.3       21.3       76.2     24.4     34.4'
...         ...       ....     .....    .....


could you please suggest. 

thanks
kumar.
 



--- Kent Johnson <kent37 at tds.net> wrote:

> This will only output the data from the first line
> of each file in the 
> source directory. If the files have multiple lines,
> you need another 
> loop. see below.
> 
> Also you can make a string with a tab in it with
> '\t', maybe more 
> readable than this: '	'
> 
> Kent
> 
> John Purser - Gmail wrote:
> > Morning Kumar,
> > 
> > This worked for me:
> > ###Code Start###
> > import os
> > path = 'C:\\Documents and Settings\\WHOEVER\\My
> Documents\\temp\\'
> > files = os.listdir(path)
> > out = file('output.txt', 'w')
> > 
> > for inFile in files:
> > 	f = file(path + inFile, 'r')
> 	for line in f:
> 	 	b = line.split('	')	#There's a tab in there, not
> spaces
> 	 	if len(b) >= 3:
> 	 		out.write(b[3] + '\n')
> > 	f.close()
> > 
> > out.close()
> > 
> > ###Code End###
> > 
> > 
> > I'd give the output file an output directory of
> it's own to be sure I didn't
> > clobber anything and of course those are windows
> directory seperators.
> > 
> > John Purser
> > 
> > -----Original Message-----
> > From: tutor-bounces at python.org
> [mailto:tutor-bounces at python.org]On
> > Behalf Of kumar s
> > Sent: Tuesday, November 23, 2004 05:38
> > To: tutor at python.org
> > Subject: [Tutor] how to select a column from all
> files in one directory?
> > 
> > 
> > Dear group,
> >  I have ~40 tab-delimitted text files in one
> > directory. I have to select 4th column from all
> these
> > files and write it into a single tab delimitted
> text
> > file. How can I do this in python.
> > 
> > I read a prev. post on tutor and tried the
> following:
> > 
> > 
> >>>files = listdir('path')
> > 
> > 
> > This returns the files(file names) in the
> directory as
> > a list. However, I need the 4th column from all
> the
> > files in the directory.
> > 
> > Can you please help me.
> > 
> > Thank you.
> > 
> > -kumar
> > 
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