二维numpy ndarray的交集 [英] Intersection of 2D numpy ndarrays

问题描述

我有一个问题.

我有两个numpy数组，它们是OpenCV凸包，并且我想检查交集而不创建循环或创建图像并对其执行numpy.bitwise_and，这两个函数在Python中都非常慢.数组如下所示:

I have two numpy arrays that are OpenCV convex hulls and I want to check for intersection without creating for loops or creating images and performing numpy.bitwise_and on them, both of which are quite slow in Python. The arrays look like this:

[[[x1 y1]]
 [[x2 y2]]
 [[x3 y3]]
...
 [[xn yn]]]

考虑[[x1 y1]]作为一个元素，我想在两个numpy ndarray之间执行交集.我怎样才能做到这一点?我发现了一些性质相似的问题，但是我无法从那里找出解决方案.

Considering [[x1 y1]] as one single element, I want to perform intersection between two numpy ndarrays. How can I do that? I have found a few questions of similar nature, but I could not figure out the solution to this from there.

提前谢谢！

推荐答案

这就是我要做的工作:

import Polygon, numpy

# Here I extracted and combined some contours and created a convex hull from it.
# Now I wanna check whether a contour acquired differently intersects with this hull or not.

for contour in contours:  # The result of cv2.findContours is a list of contours
    contour1 = contour.flatten()
    contour1 = numpy.reshape(contour1, (int(contour1.shape[0]/2),-1))
    poly1 = Polygon.Polygon(contour1)

    hull = hull.flatten()  # This is the hull is previously constructued
    hull = numpy.reshape(hull, (int(hull.shape[0]/2),-1))
    poly2 = Polygon.Polygon(hull)

    if (poly1 & poly2).area()<= some_max_val:
        some_operations

我不得不使用for循环，尽管它给了我预期的结果，但是这看起来有点乏味.任何更好的方法将不胜感激！

I had to use for loop, and this altogether looks a bit tedious, although it gives me expected results. Any better methods would be greatly appreciated!

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