以某种方式获得矩阵的一些行 [英] Pythonic way to get some rows of a matrix

问题描述

我正在考虑几年前在Python中编写的代码，在某些时候，它必须通过索引列表的列表来获取一些元素。

I was thinking about a code that I wrote a few years ago in Python, at some point it had to get just some elements, by index, of a list of lists.

我记得我做了这样的事情：

I remember I did something like this:

def getRows(m, row_indices):
    tmp = []
    for i in row_indices:
        tmp.append(m[i])
    return tmp

现在我已经学习了一点点以后，我将使用一个列表推导，如下：

Now that I've learnt a little bit more since then, I'd use a list comprehension like this:

[m[i] for i in row_indices]

想知道是否有更多的pythonic的方式来做到。任何想法？

But I'm still wondering if there's an even more pythonic way to do it. Any ideas?

我想知道也可以使用numpy o任何其他数组库。

I would like to know also alternatives with numpy o any other array libraries.

推荐答案

值得看看 NumPy 的切片语法。在链接的页面中向下滚动，直到您转到索引，切片和迭代。

It's worth looking at NumPy for its slicing syntax. Scroll down in the linked page until you get to "Indexing, Slicing and Iterating".

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