在MATLAB中无需for循环即可扫描每一列 [英] Scan each column without for loop in MATLAB

问题描述

I = [2 1];
A = [7 11
     8 17];

如何在没有for循环的情况下在A中选择正确的值? I是A中每一列的索引向量.那是I(1) is 8和I(2) = 11.

How can I pick the right value in A without for loop? I is a vector of indices for each column in A. That is I(1) is 8 and I(2) = 11.

推荐答案

使用 sub2ind 生成基于右行和列坐标的线性索引，然后使用它们索引到A.在这种情况下，I选择右行，并且您只希望从第一列到最后一列为每个列选择一个元素:

Use sub2ind to generate linear indices based on the right row and column coordinates, then use these to index into A. In this case, I chooses the right row and you want to choose only one element for each column from the first up to the last:

ind = sub2ind(size(A), I, 1:numel(I));
out = A(ind);

示例

>> I = [2 1];
>> A = [7 11
        8 17];
>> ind = sub2ind(size(A), I, 1:numel(I));
>> out = A(ind);
>> out

out =

     8    11

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