numpy.bincount() in Python (original) (raw)

Last Updated : 17 Nov, 2020

In an array of +ve integers, the numpy.bincount() method counts the occurrence of each element. Each bin value is the occurrence of its index. One can also set the bin size accordingly. Syntax :

numpy.bincount(arr, weights = None, min_len = 0)

Parameters :

arr : [array_like, 1D]Input array, having positive numbers weights : [array_like, optional]same shape as that of arr min_len : Minimum number of bins we want in the output array

Return :

Output array with no. of occurrence of index value of bin in input - arr. Output array, by default is of the length max element of arr + 1. Here size of the output array would be max(input_arr)+1.

Code 1 : Working of bincount() in NumPy

Python3 `

Python Program explaining

working of numpy.bincount() method

import numpy as geek

1D array with +ve integers

array1 = [1, 6, 1, 1, 1, 2, 2] bin = geek.bincount(array1) print("Bincount output : \n ", bin) print("size of bin : ", len(bin), "\n")

array2 = [1, 5, 5, 5, 4, 5, 5, 2, 2, 2] bin = geek.bincount(array2) print("Bincount output : \n ", bin) print("size of bin : ", len(bin), "\n")

using min_length attribute

length = 10 bin1 = geek.bincount(array2, None, length) print("Bincount output : \n ", bin1)

print("size of bin : ", len(bin1), "\n")

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Output :

Bincount output : [0 4 2 0 0 0 1] size of bin : 7

Bincount output : [0 1 3 0 1 5] size of bin : 6

Bincount output : [0 1 3 0 1 5 0 0 0 0] size of bin : 10

Code 2 : We can perform addition as per element with bincount() weight

Python3 `

Python Program explaining

working of numpy.bincount() method

import numpy as geek

1D array with +ve integers

array2 = [10, 11, 4, 6, 2, 1, 9] array1 = [1, 3, 1, 3, 1, 2, 2]

array2 : weight

bin = geek.bincount(array1, array2) print("Summation element-wise : \n", bin)

#index 0 : 0 #index 1 : 10 + 4 + 2 = 16 #index 2 : 1 + 9 = 10 #index 3 : 11 + 6 = 17

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