x和y数组点的笛卡尔积变成2D点的单个数组 [英] Cartesian product of x and y array points into single array of 2D points

问题描述

我有两个numpy数组，它们定义了网格的x和y轴.例如:

I have two numpy arrays that define the x and y axes of a grid. For example:

x = numpy.array([1,2,3])
y = numpy.array([4,5])

我想生成这些数组的笛卡尔积以生成:

I'd like to generate the Cartesian product of these arrays to generate:

array([[1,4],[2,4],[3,4],[1,5],[2,5],[3,5]])

这并不是一种非常低效的方式，因为我需要循环执行多次.我假设将它们转换为Python列表并使用itertools.product并返回到numpy数组并不是最有效的形式.

In a way that's not terribly inefficient since I need to do this many times in a loop. I'm assuming that converting them to a Python list and using itertools.product and back to a numpy array is not the most efficient form.

推荐答案

>>> numpy.transpose([numpy.tile(x, len(y)), numpy.repeat(y, len(x))])
array([[1, 4],
       [2, 4],
       [3, 4],
       [1, 5],
       [2, 5],
       [3, 5]])

请参见使用numpy进行构建一个由两个数组的所有组合组成的数组，这是用于计算N个数组的笛卡尔积的一般解决方案.

See Using numpy to build an array of all combinations of two arrays for a general solution for computing the Cartesian product of N arrays.

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