问题描述
我有一个矩阵，例如
A = [ 1 2 3; 4 5 6; 7 8 9] ;
和一个大小为 1x3 的向量，它指定每行中的哪个元素是我正在寻找的元素 - 即如果
and a vector of size 1x3 which specifies which element in each row is the one I'm looking for - i.e. If
vector = [ 1 2 1 ]
那么所需的输出是
[ 1 5 7 ]
因为 1 是第一行的第一元素，5 是第二行的第二元素，7 是第 3 行中的第 1 个元素.
since 1 is the 1'st element in the 1'st row, 5 is the 2'nd in the 2'nd row, and 7 is the 1'st element in the 3'rd row.
我如何实现这一目标?找不到可以执行此操作的内置函数，这让我感到惊讶.
How do I achieve this? Couldn't find a built in function to do this, which surprised me.
推荐答案
首先，Matlab中的索引是自上而下的.
所以在你的情况下 A[1] = 1 , A[2] = 4 , A[3] = 7
First of all, the indexes in Matlab go from top to bottom.
So in your case A[1] = 1 , A[2] = 4 , A[3] = 7
也就是说，在 A' 上工作会更容易，因为它更微不足道.
That said, it would be easier to work on A' , because its a bit more trivial.
B = A';
B((vector + [0:2].* 3))
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