formatting file

[Peter Otten]

SPJ wrote:

> test1    1.1-1   installed
> test1    1.1-1   update
> test2    2.1-1   installed
> test2    2.1-2   update
> 
> I want the file to be formatted in the following way:
> 
> test1    1.1-1   1.1-2
> test2    2.1-1   2.1-2

The following program expects a sorted input file:

import itertools
from operator import itemgetter

def pivot(infile, outfile, 
          getkey=itemgetter(0), getvalue=itemgetter(1), sep="\t"):
    if not hasattr(infile, "read"):
        infile = file(infile)
    if not hasattr(outfile, "write"):
        outfile = file(outfile, "w")

    records = (line.split() for line in infile)
    for key, items in itertools.groupby(records, getkey):
        out_record = [key]
        out_record.extend(getvalue(item) for item in items)
        print >> outfile, sep.join(out_record)

if __name__ == "__main__":
    import sys
    infile, outfile = sys.argv[1:]
    if infile == "-": infile = sys.stdin
    if outfile == "-": outfile = sys.stdout
    pivot(infile, outfile)