我该如何"zip排序"?并行的numpy数组? [英] How can I "zip sort" parallel numpy arrays?

问题描述

如果我有两个并行列表，并希望按照第一个中的元素顺序对其进行排序，则非常简单:

If I have two parallel lists and want to sort them by the order of the elements in the first, it's very easy:

>>> a = [2, 3, 1]
>>> b = [4, 6, 7]
>>> a, b = zip(*sorted(zip(a,b)))
>>> print a
(1, 2, 3)
>>> print b
(7, 4, 6)

如何使用numpy数组执行相同操作而又不将其解包到常规Python列表中?

How can I do the same using numpy arrays without unpacking them into conventional Python lists?

推荐答案

b[a.argsort()]应该可以解决问题.

这是它的工作方式.首先，您需要找到排序为a的排列. argsort是一种计算方法:

Here's how it works. First you need to find a permutation that sorts a. argsort is a method that computes this:

>>> a = numpy.array([2, 3, 1])
>>> p = a.argsort()
>>> p
[2, 0, 1]

您可以轻松地检查这是否正确:

You can easily check that this is right:

>>> a[p]
array([1, 2, 3])

现在将相同的排列应用于b.

Now apply the same permutation to b.

>>> b = numpy.array([4, 6, 7])
>>> b[p]
array([7, 4, 6])

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