我如何计算以下数组中的0和1的数量?

y = np.array([0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1])

y.count(0)为:

numpy。Ndarray对象没有属性计数


当前回答

Numpy为此提供了一个模块。只是一个小hack。将输入数组作为箱子。

numpy.histogram(y, bins=y)

输出是2个数组。一个是数值本身,另一个是相应的频率。

其他回答

一个普遍而简单的答案是:

numpy.sum(MyArray==x)   # sum of a binary list of the occurence of x (=0 or 1) in MyArray

这将导致这完整的代码作为例子

import numpy
MyArray=numpy.array([0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1])  # array we want to search in
x=0   # the value I want to count (can be iterator, in a list, etc.)
numpy.sum(MyArray==0)   # sum of a binary list of the occurence of x in MyArray

现在,如果MyArray是多维的,你想要计算值在直线(= pattern以后)上分布的次数。

MyArray=numpy.array([[6, 1],[4, 5],[0, 7],[5, 1],[2, 5],[1, 2],[3, 2],[0, 2],[2, 5],[5, 1],[3, 0]])
x=numpy.array([5,1])   # the value I want to count (can be iterator, in a list, etc.)
temp = numpy.ascontiguousarray(MyArray).view(numpy.dtype((numpy.void, MyArray.dtype.itemsize * MyArray.shape[1])))  # convert the 2d-array into an array of analyzable patterns
xt=numpy.ascontiguousarray(x).view(numpy.dtype((numpy.void, x.dtype.itemsize * x.shape[0])))  # convert what you search into one analyzable pattern
numpy.sum(temp==xt)  # count of the searched pattern in the list of patterns

对于您的情况,还可以查看numpy.bincount

In [56]: a = np.array([0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1])

In [57]: np.bincount(a)
Out[57]: array([8, 4])  #count of zeros is at index 0, i.e. 8
                        #count of ones is at index 1, i.e. 4
using numpy.count

$ a = [0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1]

$ np.count(a, 1)

因为ndarray只包含0和1, 您可以使用sum()来获得1的出现次数 和len()-sum()来得到0的出现情况。

num_of_ones = sum(array)
num_of_zeros = len(array)-sum(array)

这个函数返回变量在数组中出现的次数:

def count(array,variable):
    number = 0
    for i in range(array.shape[0]):
        for j in range(array.shape[1]):
            if array[i,j] == variable:
                number += 1
    return number