import collections

​

arr = ['a', 'a', 'b', 'b', 'b', 'c']

​

# set the elements frequencies using Counter class

elements_count = collections.Counter(arr)

​

# printing the element and the frequency

for key, value in elements_count.items():

    print(f"{key}: {value}")

​

# output

# a: 2

# b: 3

# c: 1

​

​

data = 'hello world'

​

# set the elements frequencies using Counter class

elements_count = collections.Counter(data)

​

# printing the element and the frequency

print(elements_count)

from collections import Counter

strl = "aabbaba"

print(Counter(str1))

​

Counter({'a': 4, 'b': 3})

​

# PYTHON 3

from collections import Counter

def example(data: str) -> Counter:

    counted_letters = Counter(data) # Counts every character in the string

    return counted_letters # {character: amount}

example('Data1233') # Counter({'D': 1, 'a': 2, 't': 1, '1': 1, '2': 1, '3': 2})

example('hello world') # Counter({'h': 1, 'e': 1, 'l': 3, 'o': 2, ' ': 1, 'w': 1, 'r': 1, 'd': 1})

import collections

​

c = collections.Counter()

print 'Initial :', c

​

c.update('abcdaab')

print 'Sequence:', c

​

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

print 'Dict    :', c

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)

​

>>> from collections import Counter

>>> colors = ['blue', 'blue', 'blue', 'red', 'red']

>>> counter = Counter(colors)

>>> counter['yellow'] += 1

Counter({'blue': 3, 'red': 2, 'yellow': 1})

>>> counter.most_common()[0]

('blue', 3)

import collections

​

number = [0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1]

collections.Counter(number)

​

#output

#Counter({0: 12, 1: 9})

>>> # Tally occurrences of words in a list

>>> cnt = Counter()

>>> for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']:

...     cnt[word] += 1

>>> cnt

Counter({'blue': 3, 'red': 2, 'green': 1})

​

>>> # Find the ten most common words in Hamlet

>>> import re

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

>>> 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)]

>>> Counter('abracadabra').most_common(3)

[('a', 5), ('r', 2), ('b', 2)]

​

sum(c.values())                 # total of all counts

c.clear()                       # reset all counts

list(c)                         # list unique elements

set(c)                          # convert to a set

dict(c)                         # convert to a regular dictionary

c.items()                       # convert to a list of (elem, cnt) pairs

Counter(dict(list_of_pairs))    # convert from a list of (elem, cnt) pairs

c.most_common()[:-n-1:-1]       # n least common elements

c += Counter()                  # remove zero and negative counts

​