Python: collections.Counter()

[sophryu99]

Initialization of Counter class

import collections
print collections.Counter(['a', 'b', 'c', 'a', 'b', 'b'])
print collections.Counter({'a':2, 'b':3, 'c':1})
print collections.Counter(a=2, b=3, c=1)
>>> Counter({'b': 3, 'a': 2, 'c': 1})
>>> Counter({'b': 3, 'a': 2, 'c': 1})
>>> Counter({'b': 3, 'a': 2, 'c': 1})

Time Complexity: O(n)

[sophryu99]

Create and Update Counters

c = collections.Counter()
print 'Initial :', c

c.update('abcdaab')
print 'Sequence:', c

c.update({'a':1, 'd':5})
print 'Dict    :', c

Find the most common words

import re

words = re.findall('w+', open('hamlet.txt').read().lower())

print Counter(words).most_common(10)

[('the', 1143), ('and', 966), ('to', 762), ('of', 669), ('i', 631),
 ('you', 554),  ('a', 546), ('my', 514), ('hamlet', 471), ('in', 451)]