006 Python Cookbook 01-12 Most Frequently Items

#!/usr/bin/env python

# http://chimera.labs.oreilly.com/books/1230000000393/ch01.html#_determining_the_most_frequently_occurring_items_in_a_sequence
# 1.12 determining the most frequently occurring items in a sequence

from collections import Counter def test_Counter():   artical1 = [     'As', 'a', 'news', 'aggregator', 'site', 'Google', 'uses',     'its', 'own', 'software', 'to', 'determine', 'which',     'stories', 'to', 'show', 'from', 'the', 'online', 'news',     'sources', 'it', 'watches', 'Human', 'editorial', 'input',     'does', 'come', 'into', 'the', 'system,', 'however,', 'in',     'choosing', 'exactly', 'which', 'sources', 'Google', 'News',     'will', 'pick', 'from.', 'This', 'is', 'where', 'some', 'of',     'the', 'controversy', 'over', 'Google', 'News', 'originates,',     'when', 'some', 'news', 'sources', 'are', 'included', 'when',     'visitors', 'feel', 'they', 'dont', 'deserve', 'it', 'and',     'when', 'other', 'news', 'sources', 'are', 'excluded', 'when',     'visitors', 'feel', 'they', 'ought', 'to', 'be', 'included',     'For', 'examples,', 'see', 'the', 'above', 'mentions', 'of',     'Indymedia,', 'or', 'National',   ]   artical2 = [     'from', 'somewhere', 'to', 'sometime', 'to', 'somebody'   ]      # Counter works on all sequence of hashable inout items   word_counts_1 = Counter(artical1)   top_five = word_counts_1.most_common(5)   print "artical1 top_five =", top_five   for (key, value) in dict(top_five).items():     print " %s = %d " % (key, value)        print "----------"   word_counts_2 = Counter(artical2)   top_five = word_counts_2.most_common(5)   print "artical2 top_five =", top_five   for (key, value) in dict(top_five).items():     print " %s = %d " % (key, value)        print "----------"   sum_1_2 = word_counts_1 + word_counts_2   top_five = sum_1_2.most_common(5)   print "artical1 + artical2 =", top_five      #for (key, value) in dict(top_five).items():   # refined for better performance (by reducing memory copy)   for (key, value) in dict(top_five).iteritems():     print " %s = %d " % (key, value)   if __name__ == "__main__":   test_Counter()

artical1 top_five = [('sources', 4), ('when', 4), ('news', 4), ('the', 4), ('to', 3)]  sources = 4   the = 4   when = 4   to = 3   news = 4  ---------- artical2 top_five = [('to', 2), ('somewhere', 1), ('sometime', 1), ('from', 1), ('somebody', 1)]  somewhere = 1   to = 2   sometime = 1   from = 1   somebody = 1  ---------- artical1 + artical2 = [('to', 5), ('sources', 4), ('when', 4), ('news', 4), ('the', 4)]  to = 5   news = 4   when = 4   the = 4   sources = 4