"fynali" wrote: > Is a rewrite possible of Raymond's or Fredrik's suggestions above which > will still give me the time saving made?
Python 2.2 don't have a readymade set type (new in 2.3), and it doesn't support generator expressions (the thing that caused the syntax error). however, using a dictionary instead of the set barred = {} for number in open(open('/home/sjd/python/wip/CBR0000319.dat')): barred[number] = None # just add it as a key and a list comprehension instead of the generator expression outfile.writelines([number for number in infile if number not in barred]) (note the extra brackets) should give you decent performance under 2.2. </F> -- http://mail.python.org/mailman/listinfo/python-list