Delete or remove last column in CSV file using Python

I have a CSV file with 5 columns. Using Python, how can I delete the last column (header5 in the example)? Is there an easy way I'm missing, or do I have to loop through all rows in the CSV and remove each value from the last column (which could still leave me with the undesired preceding comma)?

I'm not seeing anything related to this in the CSV module or elsewhere on the interwebs, so any help is much appreciated.

header1,header2,header3,header4,header5
value1,value开发者_JAVA百科2,value3,value4,value5
value1,value2,value3,value4,value5

Use the csv module. When writing out a row, use row[:-1] to chop off the last item:

import csv

with open(filename,"r") as fin:
    with open(outname,"w") as fout:
        writer=csv.writer(fout)
        for row in csv.reader(fin):
            writer.writerow(row[:-1])

Even if you don't use CSV module, the logical and sane way is to read the file row by row, split them on comma, and print out item 1 through 4 with a join. eg

for line in open("file"):
    print ','.join( line.split(",")[:-1] )

Or just by simple string indexing

for line in open("file"):
    print line[ : line.rindex(",") ]