為numpy數組的slice的奇數和偶數元素分配不同的值

Question

是否可以為numpy數組切片的偶數和奇數元素分配不同的值？

將起作用的代碼示例：

a=np.zeros(100)
b=np.arange(10,50,10)

print(a)
[0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.
 0. 0. 0. 0.]

a[b]=10

print(a)

[ 0.  0.  0.  0.  0.  0.  0.  0.  0.  0. 10.  0.  0.  0.  0.  0.  0.  0.
  0.  0. 10.  0.  0.  0.  0.  0.  0.  0.  0.  0. 10.  0.  0.  0.  0.  0.
  0.  0.  0.  0. 10.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.
  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.
  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.
  0.  0.  0.  0.  0.  0.  0.  0.  0.  0.]

現在，我正在嘗試為切片a [b]的偶數和奇數元素分配不同的數字

a[b][::2] = 10

a[b][1::2] = -10

但這是行不通的，初始的零數組不會修改。

簡短通知-實際上，b和a是動態生成的，因此我通常不知道它們的形狀（a和b）以及哪些索引在（b）內

Answer 1

您應該直接索引b ：

import numpy as np

a = np.zeros(100)
b = np.arange(10,50,10)

a[b[::2]] = 10
a[b[1::2]] = -10

print(a[b])
# [ 10. -10.  10. -10.]