Python list group by count

Find frequency of numbers in list python

from collections import Counter

def frequency_table(n):
    table = Counter(n)
    print('Number\tFrequency')
    for number in table.most_common() :
        print('{0}\t{1}'.format(number[0], number[1]))
        
# src : Doing Math With Python

List count frequency python

import collections
a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
counter=collections.Counter(a)
print(counter)
# Counter({1: 4, 2: 4, 3: 2, 5: 2, 4: 1})
print(counter.values())
# [4, 4, 2, 1, 2]
print(counter.keys())
# [1, 2, 3, 4, 5]
print(counter.most_common(3))
# [(1, 4), (2, 4), (3, 2)]

Source: stackoverflow.com

How to get count by using group by in python

df[['col1', 'col2', 'col3', 'col4']].groupby(['col1', 'col2']).agg(['mean', 'count'])

Source: stackoverflow.com

Python list group by count

>>> a = [1,1,1,1,2,2,2,2,3,3,4,5,5]
>>> d = {x:a.count(x) for x in a}
>>> d
{1: 4, 2: 4, 3: 2, 4: 1, 5: 2}
>>> a, b = d.keys(), d.values()
>>> a
[1, 2, 3, 4, 5]
>>> b
[4, 4, 2, 1, 2]

Source: stackoverflow.com

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