How I can find index of element in array?

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Mykhailo Yaroshenko on 8 Nov 2017

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Commented: •Partovion 2 Oct 2021

Accepted Answer: James Tursa

I know, that number, for example, 5, is an element in array X, but I don't know it's index. In Python, I can use:

X.index(5)

I realized this function, using for loop and if statement, but did Matlab doesn't have build-in similar function?

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James Tursa on 8 Nov 2017

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Edited:James Tursa on 8 Nov 2017

If you know the number exactly , then you can use:

result = find(X==5);

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•Partovi on 2 Oct 2021

The function find() is useful as far as matrices (2-D tensors) are concerned. I cannot, however, find a useful function for nd-arrays where, for instance, the index could be an array on its own. See example below:

M = reshape(1:24, [2,3,4]);

indices = index_finder(M==20); % indices = vector of indices

It would be very useful if there was a function which worked for tensors of any dimensionality.

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