从另一个数组的索引中获取数组的值:Matlab [英] Get the values of an array from indices in another array: Matlab

问题描述

我有一个20x1的双精度数组A和一个1000x1的双精度数组B.

I have a 20x1 double array A, and a 1000x1 double array B.

我想获取数组C，其中数组C将是1000x1的两倍，其中B中的值用于索引A中的值，如下所示:

I want to get array C, where array C will be 1000x1 double where the values in B are used to index the values in A like so:

C(1) = A(B(1))
C(2) = A(B(2))
...
C(i) = A(B(i))
...
c(1000) = A(B(1000))

这怎么办?

推荐答案

您不需要为此循环，可以直接使用:

You don't need a loop for this, you can directly use:

C = A(B)

这利用了MATLAB的矩阵索引，这是使用数组而不是整数时在MATLAB中处理索引的方式.

This takes advantage of MATLAB's matrix indexing, which is the way indexing is handled in MATLAB when an array is used instead of an integer.

看一下文档: https://uk. mathworks.com/help/matlab/math/matrix-indexing.html

例如:

A = [11 12 13];
B = [1 2 3 1 2 3 3 2 1];
C = A(B)

C =

11    12    13    11    12    13    13    12    11

确保B仅包含作为A的有效索引的整数(不少于1或大于A的长度).

Ensure that B only contains integers which are valid indices of A (not less than 1 or greater than the length of A).

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