如何找到元素数组的索引数组? [英] How to find the index array of a array of elements?

问题描述

我想用一个例子来展示我想要的东西.

I'd like to use an example to show what I want.

A = [5 1 2 4 3]; % of distinct values

B = [3 3 1 5 2];

我可以找到在MATLAB中实现的库函数吗?

Can I find a library function implemented in MATLAB such that:

C = [5 5 2 3 1] = someFun(A, B)

即C(i) = find(A == B(i))

请注意，我要的是库函数，因为在这种情况下，它是高度优化的.如果您确定不存在这样的功能，那也是答案.

Note that I am asking for a library function, as in that case it is highly optimized. If you are sure there doesn't exist such a function, that is also an answer.

推荐答案

几个解决方案:

C = zeros(size(B));
for i=1:numel(B)
    C(i) = find(A == B(i));
end

arrayfun

C = arrayfun(@(n)find(A==n), B)

使用BSXFUN进行向量化的相等性

[C,~] = find( bsxfun(@eq, B, A.') )

成员

[~,C] = ismember(B,A)

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