如何转换/移动一个numpy数组? [英] How to translate / shift a numpy array?

问题描述

我不确定要搜索什么关键字，因此如果已经被询问，请链接响应并关闭该线程.

I am not sure what key-word to search for so if it has been already asked please link the response and close this thread.

我正在尝试将numpy数组的非零条目按固定方向移动，例如，假设我有一个2d数组:

I am trying to shift the non-zero entries of a numpy array by a fixed direction, for instance, imagine I have a 2d array:

0 1 2 0
0 3 0 0
0 0 0 0
0 0 0 0

将其移动(1,1)将产生以下数组:

Shifting it by (1,1) would produce the following array:

0 0 0 0
0 0 1 2
0 0 3 0
0 0 0 0

让我们说如果非零条目超出范围，则将它们简单地丢弃.我该怎么办?

Let's say if the non-zero entries goes out of bound they're simply dropped. How might I do this?

显然与此有些重复? 移动numpy数组中的元素 我真的看不出它们为什么是一个完全相同的问题，因为那个人谈论的是使事情无限循环，所以这更多的是滚动"动作而不是转移.我也喜欢这里的解决方案，它非常简单易读.

edit: aparently some duplicate from this? Shift elements in a numpy array I don't really see why are they the same question at all because that one talks about looping the things out of bound around, so it's more of a "rolling" action rather than shifting. Also I liked the solution here, it is very simple and readable.

再次修复了某些格式

推荐答案

要简单地管理边缘，可以将数组扩大到更大:

To simply manage the edges, you can enlarge your array in a bigger one :

square=\
array([[0, 2, 2, 0],
       [0, 2, 0, 0],
       [0, 0, 0, 0],
       [0, 0, 0, 0]], dtype=int64)

n,m=square.shape
bigsquare=np.zeros((3*n,3*m),square.dtype) 
bigsquare[n:2*n,m:2*m]=square

然后转移只是一个视图:

Then shift is just a view :

def shift(dx,dy):
    x=n-dx
    y=m-dy
    return bigsquare[x:x+n,y:y+m]

print(shift(1,1))

#[[0 0 0 0]
# [0 0 2 2]
# [0 0 2 0]
# [0 0 0 0]]

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