在Python中使用切片更改多个Numpy数组元素 [英] Changing multiple Numpy array elements using slicing in Python

问题描述

说我有 numpy 数组 arr_1 = np.arange(10)返回:

array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

如何使用切片将多个元素更改为某个值?

How do I change multiple elements to a certain value using slicing?

例如:将从第一个元素开始的每五个元素中出现的第零个，第一个和第二个元素更改为100.我想要这样做:

For example: changing the zeroth, first and second element that occur every five elements, starting from the first element, to 100. I want this:

array([0, 100, 100, 100, 4, 5, 100, 100, 100, 9])

我尝试了 arr_1 [1 :: [5，6，7]] = 100 ，但这不起作用.

I tried arr_1[1::[5, 6, 7]] = 100 but that doesn't work.

推荐答案

这是使用使用原始样品运行样品-

Sample run with original sample -

In [849]: a = np.arange(10)       # Input array
     ...: idx = np.array([0,1,2]) # Indices to be set
     ...: offset = 1              # Offset
     ...: 
     ...: a[np.in1d(np.mod(np.arange(a.size),5) , idx+offset)] = 100
     ...: 

In [850]: a
Out[850]: array([  0, 100, 100, 100,   4,   5, 100, 100, 100,   9])

使用非顺序索引-

In [851]: a = np.arange(11)       # Input array
     ...: idx = np.array([0,2,3]) # Indices to be set
     ...: offset = 1              # Offset
     ...: 

In [852]: a[np.in1d(np.mod(np.arange(a.size),5) , idx+offset)] = 100

In [853]: a
Out[853]: array([  0, 100,   2, 100, 100,   5, 100,   7, 100, 100,  10])

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