如何在矩阵前添加一列? [英] How to prepend a column to a matrix?

问题描述

好吧，假设我有这个矩阵:{{1,2}，{2,3}}，而我宁愿有{{4,1,2}，{5,2,3}}.也就是说，我在矩阵的前面添加了一个列.有简单的方法吗?

Ok, imagine I have this Matrix: {{1,2},{2,3}}, and I'd rather have {{4,1,2},{5,2,3}}. That is, I prepended a column to the matrix. Is there an easy way to do it?

我最好的建议是这样

PrependColumn[vector_List, matrix_List] := 
 Outer[Prepend[#1, #2] &, matrix, vector, 1]

但是它混淆了代码，并不断要求加载越来越多的代码.这不是内置的吗?

But it obfuscates the code and constantly requires loading more and more code. Isn't this built in somehow?

推荐答案

由于在Mathematica 6中引入了ArrayFlatten，所以必须使混淆最少的解决方案是

Since ArrayFlatten was introduced in Mathematica 6 the least obfuscated solution must be

matrix = {{1, 2}, {2, 3}}
vector = {{4}, {5}}

ArrayFlatten@{{vector, matrix}}

一个不错的技巧是用0替换任何矩阵块都会得到大小合适的零块.

A nice trick is that replacing any matrix block with 0 gives you a zero block of the right size.

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