CODEWITHSUNDEEP
matlab
Mace
Mace

Reputation: 1269

Subset array to members of another array in Matlab

I am looking for a functionality i Matlab to subset and array like the IN function in SQL or %in% in R. I.e. I have the following data:

a = 1:3;
b = 2:4;

Then I want to write something like:

(a %in% b)

And it should produce:

ans =

     0     1     1

However using %in% clearly doesn't work.

Upvotes: 1

Views: 87

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112659

You could also do it with bsxfun:

result = sum(bsxfun(@eq, a(:).', b(:)), 1);

This has the advantage that it tells you how many elements of b equal each element of a. For example,

>> a = [1 2 3];
>> b = [2 3 4 2];
>> result = sum(bsxfun(@eq, a(:).', b(:)),1)
result =
     0     2     1

Upvotes: 1

Nras
Nras

Reputation: 4311

You are probably looking for the function ismember, which checks which members of one matrix are also member of a second matrix. It returns true/false for each entry in your matrix a if it can/cannot be found in your matrix b.

ismember(a, b)
ans =

0     1     1

As a side note: % is the character, which starts a comment.

Upvotes: 3

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