easy questions from python newbie

[James Stroud]

walterbyrd wrote:
> This is the first real python program I have ever worked on. What I
> want to do is:
> 1) count identical records in a cvs file
> 2) create a new file with quantities instead duplicate records
> 3) open the new file in ms-excel
> 
> For example, I will start with a file like:
> 
> 1001
> 1012
> 1008
> 1012
> 1001
> 1001
> 
> and finish with a file like:
> 
> 1001,3
> 1008,1
> 1012,2
> 
> What I need to know:
> 1) is there a function in python that will sort a file into another
> file. Something like:
> sort file1.txt > file2.txt from the DOS command line. I know there is
> also a similar "sort" funtion in Unix.

import os
os.system('sort file1.txt > file2.txt')

> 2) is there a function in python that will correctly load a csv file
> into an excel spreadsheet,
> and open that spreadsheet.

What's with the excel files? You must be in industry. Excel opens csv 
files, no problem. In Mac OS X, you can do this:

   os.system('open -a /Applications/Excel %s' % 'my_file.csv')

It probably requires a nauseating journey through a bunch of hoops to do 
the equivalent in window$. But you haven't specified your operating 
system, so I optimistically assume a best-case (OS X) and not a 
worst-case (window$). If worst-case, I'm truly sorry for your misfortune.

> 3) I will probably be working with 50 items, or less, would it be best
> for me to do this with a
> multi-diminsional array? For example: sort the file, read a rec into
> the array, if the next rec is the same then incr the count, otherwise
> add a new rec with a count of 1. Then write the array to a file?
> 

Ah, a real question. Use a dict:

if adict.has_key(some_key):
   adict[some_key] += 1
else:
   adict[some_key] = 1

James



-- 
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/