是否有一个＆QUOT;边框＆QUOT;功能（切片非零值）在numpy的一个ndarray？ [英] Is there a "bounding box" function (slice with non-zero values) for a ndarray in NumPy?

问题描述

我处理通过numpy.array（）创建的阵列中，我需要一个画布模拟图像上画点。因为有很多零值的周围包含有意义的数据阵列的中心部分，我想调整阵列，擦除只包含零和行只包含零的列

I am dealing with arrays created via numpy.array(), and I need to draw points on a canvas simulating an image. Since there is a lot of zero values around the central part of the array which contains the meaningful data, I would like to "trim" the array, erasing columns that only contain zeros and rows that only contain zeros.

所以，我想知道一些本地numpy的功能，甚至是code段，以调整还是找到了边框切片只有数组的包含数据的部分。

So, I would like to know of some native numpy function or even a code snippet to "trim" or find a "bounding box" to slice only the data-containing part of the array.

（因为它是一个概念性的问题，我没有把任何code，对不起，如果我应该，我很新鲜的SO发布。）

(since it is a conceptual question, I did not put any code, sorry if I should, I'm very fresh to posting at SO.)

感谢您阅读

推荐答案

这应该这样做：

from numpy import array, argwhere

A = array([[0, 0, 0, 0, 0, 0, 0],
           [0, 0, 0, 0, 0, 0, 0],
           [0, 0, 1, 0, 0, 0, 0],
           [0, 0, 1, 1, 0, 0, 0],
           [0, 0, 0, 0, 1, 0, 0],
           [0, 0, 0, 0, 0, 0, 0],
           [0, 0, 0, 0, 0, 0, 0]])

B = argwhere(A)
(ystart, xstart), (ystop, xstop) = B.min(0), B.max(0) + 1 
Atrim = A[ystart:ystop, xstart:xstop]

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