一个数字在numpy数组中出现多少次 [英] How many times a number appears in a numpy array

问题描述

我需要找到一种方法来计算从0到9的每个数字出现在使用 np.random.randint()

I need to find a way to count how many times each number from 0 to 9 appears in a random matrix created using np.random.randint()

import numpy as np
p = int(input("Length of matrix: "))
m = np.random.randint(0,9,(p,p))
print(m)

例如，如果矩阵的长度= 4

For example if length of matrix = 4

• [[3 4 6 5] [3 4 4 3] [4 2 4 8] [6 8 2 7]]

数字4出现几次?它应该返回5.

How many times does the number 4 appear? It should return 5.

推荐答案

您应该可以很简单地获得它:

You should be able to get this pretty simply:

list(m.flatten()).count(x)

另一个可能更快的选项是使用内置的numpy count_nonzero() :

Another option which is probably faster, is to use the numpy builtin count_nonzero():

np.count_nonzero(m == x)

Hooray内置函数.

Hooray builtin functions.

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