使用另一个数组索引Numpy数组的有效方法

Question

Given a Numpy array x , and an array of integers y , I want to do something equivalent to:

z = np.array(x[i] for i in y)

Is there a Numpy function/method to do this efficiently without converting back to a list?

Answer 1

If y contains indices that are valid for x , then:

z = x[y]

>>> import numpy as np
>>> x = np.arange(100)
>>> y = np.array([1, 27, 36, 98])
>>> x[y]
array([ 1, 27, 36, 98])