[Tutor] get columns from txt file

[Don Jennings]

On Jul 12, 2012, at 11:10 AM, susana moreno colomer wrote:

> Hi!
> It is attached on the email, called myprogram.txt

and, here are the contents of that file:

> #! /usr/bin/env python
> 
> 
> import os
> import fnmatch
> import csv
> 
> 
> path = '//../my_working_folder/'
> csv_out=csv.writer(open('out14.csv', 'wb'), delimiter=' ')
> files=os.listdir(path)
> 
> outfile=open('myfile1', 'w')

Here you've opened a file called "outfile" which you never use! So, of course it's blank. Just remove this line.

> output=[]
> 
> 
> for infile in files:
          columnData = []
> 	if fnmatch.fnmatch(infile, 'bb_*'):
> 		filename= os.path.join(path,infile)
> 		f=open(filename, 'r')
> 		
> 		for line in f:
> 	
> 			b=line.split('\t')
                          # remove the next line
> 			output.append(b[5].strip())
                          # instead, append to columnData list
                          columnData.append(b[5].strip())
> 		f.close()

                  # now append all of that data as a list to the output
                  output.append(columnData)

  # now, as Kent said, create "a list of row lists from the list of column lists
  # if any of the column lists are too short they will be padded with None"

  rows = map(None, *output)

  # now, write those rows to your file
  csv_out.writerows(rows)

> 
> ########This gives me a single column (I want 6, since I have 6 bb_files:
> 
> csv_out.writerows(output)

One of the things you missed in Kent's code is that the output is a list of lists. So, for each file you need a list which you then append to the output list. I've inserted the appropriate code above and you should have better luck if you copy and paste carefully.

> 
> 
> ########with this I get excel whitesheet
> 
> 
> def csvwriter():	
> 	excelfile=csv_out
> 	a=excelfile.append(output)
> 	c=excelfile.write(a)
> 	return c

Right! As I explained in an earlier email, you never call the function csvwriter; you merely define it. The file is created when you opened it earlier for writing on line 10 of your program, but you never write anything to it.

If you have the time and inclination, I recommend you work through one of the fine tutorials for python. It really is a great language and this is a **great** community of folks for people like me who are learning the language still.

Take care,
Don



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