如何使用numpy python检查数组

Question

I have two arrays and i want to check how many integers are the same in the different arrays. The problem i'm having is that it only shows me how many are the same when they are in the same position. Both arrays have 15 numbers in them. Example:

import numpy as np
a = np.array([1, 4, 5, 7, 9, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26])
b = np.array([8, 28, 12, 3, 24, 16, 23, 19, 14, 2, 11, 29, 27, 6, 13])
print(np.count_nonzero(a==b))

This prints 0 even though there's clearly integers that are the same. How can i make this print how many integers have the same value?

Answer 1

You want to use np.intersect1d , if I am understanding you correctly:

In [12]: import numpy as np

In [13]: a = np.array([1, 4, 5, 7, 9, 14, 15, 17, 18, 19, 21, 22, 23, 25, 26])
    ...: b = np.array([8, 28, 12, 3, 24, 16, 23, 19, 14, 2, 11, 29, 27, 6, 13])
    ...:

In [14]: np.intersect1d(a, b)
Out[14]: array([14, 19, 23])

Answer 2

You can perform broadcasted comparison between b and a , and then just tally up the matches:

(b == a[:, None]).sum()
3

This checks out since you have [14, 19, 23] as the common elements.