以某种方式获得矩阵的一些行

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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