collections.Counter.py

import collections
c = collections.Counter()                           # a new, empty counter
c = collections.Counter('gallahad')                 # a new counter from an iterable
c = collections.Counter({'red': 4, 'blue': 2})      # a new counter from a mapping
c = collections.Counter(cats=4, dogs=8)             # a new counter from keyword args
c = collections.Counter(['eggs', 'ham', 'ham', 'chicken'])
n = c['bacon']                 # count of a missing element is zero
c['sausage'] = 0               # counter entry with a zero count
del c['sausage']               # del actually removes the entry
print(list(c.elements()))      # elements repeating each as many times as its count.
for e in c:                    # classic looping
    print(e)
print(list(c.keys()))          # classic keys need list() cast
print(list(c.values()))        # classic values need list() cast
print(list(c.most_common(2)))  # tuples repeating each from n most common to the least
print(list(c.most_common()))   # all most common
print()

d = collections.Counter(['eggs', 'ham', 'ham', 'ham'])
print(list((c+d).most_common()))    # add two counters together:  c[x] + d[x]
print(list((c-d).most_common()))    # subtract (keeping only positive counts)
print(list((c&d).most_common()))    # intersection: min(c[x], d[x])
print(list((c|d).most_common()))    # union: max(c[x], d[x])
e = collections.Counter(['ham', 'ham', 'eggs', 'ham'])
print(d==e)    # same composition