如何为Numpy数组创建切片对象? [英] How can I create a slice object for Numpy array?

问题描述

我试图找到一个整齐的解决方案，但是我正在以相同的方式切片相同形状的几个2D数组.我已经通过定义包含'x，y'中心的列表来尽可能地整理它，例如cpix = [161, 134]我想做的是不必像这样写三遍切片:

I've tried to find a neat solution to this, but I'm slicing several 2D arrays of the same shape in the same manner. I've tidied it up as much as I can by defining a list containing the 'x,y' center e.g. cpix = [161, 134] What I'd like to do is instead of having to write out the slice three times like so:

a1 = array1[cpix[1]-50:cpix[1]+50, cpix[0]-50:cpix[0]+50] 
a2 = array2[cpix[1]-50:cpix[1]+50, cpix[0]-50:cpix[0]+50] 
a3 = array3[cpix[1]-50:cpix[1]+50, cpix[0]-50:cpix[0]+50]

只是预定义了一些内容(例如可能是面具?)，所以我可以做一个

is just have something predefined (like maybe a mask?) so I can just do a

a1 = array1[predefined_2dslice] 
a2 = array2[predefined_2dslice] 
a3 = array3[predefined_2dslice] 

这是numpy支持的吗?

Is this something that numpy supports?

推荐答案

是的，您可以使用 numpy.s_ :

Yes you can use numpy.s_:

示例:

>>> a = np.arange(10).reshape(2, 5)
>>> 
>>> m = np.s_[0:2, 3:4]
>>> 
>>> a[m]
array([[3],
       [8]])

在这种情况下:

my_slice = np.s_[cpix[1]-50:cpix[1]+50, cpix[0]-50:cpix[0]+50]

a1 = array1[my_slice] 
a2 = array2[my_slice] 
a3 = array3[my_slice]

您还可以在 numpy.r_ 中使用以便将切片对象沿第一个轴平移为串联.

You can also use numpy.r_ in order to translates slice objects to concatenation along the first axis.

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