Using find to determine equality not of scalars, but vectors
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Hi, I have two vectors say x=[1 2 3 4 5 ] and y=[2 4].
I would like to find the elements of y in x. Usually, if y is a scalar, a simple find(x==2) would do teh trick, or even x(x==2).
Is there something similar that would work like find(x==y) or x(x==y), without using a loop?
回答 (2 件)
John D'Errico 2023 年 5 月 26 日
編集済み: John D'Errico 2023 年 5 月 26 日
This is not really the province of find. Yes, you can break an egg with a hammer, but it is not really the right tool for the purpose. (Ok, yes, the scrambled eggs made that way will be high in fiber. But they tend to be a little too crunchy for my tastes.) Instead, you need to learn about the set membership tools in MATLAB.
First, I'll make the problem slightly more interesting, since using the numbers 1:5 may confuse things.
There are clearly some elements in y that are not in x, and vice versa.
[yinx,xloc] = ismember(y,x)
So which elements of y were found in x?
That makes sense. Next, where were they found?
So at locations [2,4,6] in the x vector.
You will also find the setdiff tool to be useful at times, as well as intersect and union. Spend some time familiarizing yourself with many of these fundamental tools in MATLAB. It will be well worth the time invested.
Harsh Mahalwar 2023 年 5 月 26 日
編集済み: Harsh Mahalwar 2023 年 5 月 26 日
You can use the following matlab script to find the elements of y in x without using a loop.
y = [2 4];
x = [1 2 3 4 5];
findLoc = arrayfun(@(i) find(x==i,1),y);
Here are some references,
Thanks and regards,