python如何根据给定的KEY分组

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根据给定的KEY分组(itertools.groupby)

>>> from operator import itemgetter>>> import itertools>>> with open("contactlenses.csv", "r") as infile:... data = [line.strip().split(",") for line in infile]...>>> data = data[1:]>>> def print_data(rows):... print " ".join(" ".join("{: <16}".format(s) for s in row) for row in rows)... >>> print_data(data)young myope no reduced noneyoung myope no normal softyoung myope yes reduced noneyoung myope yes normal hardyoung hypermetrope no reduced noneyoung hypermetrope no normal softyoung hypermetrope yes reduced noneyoung hypermetrope yes normal hardpre-presbyopic myope no reduced nonepre-presbyopic myope no normal softpre-presbyopic myope yes reduced nonepre-presbyopic myope yes normal hardpre-presbyopic hypermetrope no reduced nonepre-presbyopic hypermetrope no normal softpre-presbyopic hypermetrope yes reduced nonepre-presbyopic hypermetrope yes normal nonepresbyopic myope no reduced nonepresbyopic myope no normal nonepresbyopic myope yes reduced nonepresbyopic myope yes normal hardpresbyopic hypermetrope no reduced nonepresbyopic hypermetrope no normal softpresbyopic hypermetrope yes reduced nonepresbyopic hypermetrope yes normal none >>> data.sort(key=itemgetter(-1))>>> for value, group in itertools.groupby(data, lambda r: r[-1]):... print "-----------"... print "Group: " + value... print_data(group)...-----------Group: hardyoung myope yes normal hardyoung hypermetrope yes normal hardpre-presbyopic myope yes normal hardpresbyopic myope yes normal hard-----------Group: noneyoung myope no reduced noneyoung myope yes reduced noneyoung hypermetrope no reduced noneyoung hypermetrope yes reduced nonepre-presbyopic myope no reduced nonepre-presbyopic myope yes reduced nonepre-presbyopic hypermetrope no reduced nonepre-presbyopic hypermetrope yes reduced nonepre-presbyopic hypermetrope yes normal nonepresbyopic myope no reduced nonepresbyopic myope no normal nonepresbyopic myope yes reduced nonepresbyopic hypermetrope no reduced nonepresbyopic hypermetrope yes reduced nonepresbyopic hypermetrope yes normal none-----------Group: softyoung myope no normal softyoung hypermetrope no normal softpre-presbyopic myope no normal softpre-presbyopic hypermetrope no normal softpresbyopic hypermetrope no normal soft

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