give value 0 when doesn't find element without LOOP

Question

gabriele fadanelli 2020-4-10

评论： gabriele fadanelli 2020-4-10

I need to find and find the row positions of elements in a matrix for every colum and return 0 if those elements are not found, e.g.:

A=[7 6 5; 9 2 3; 2 7 1]
B=[7]
sol=sum(ismember(A,B))

gives me the result

[1 1 0]

But I wish I had [1 3 0] as result since the second 7 is in the third row.

I tried also to mutiply

sol=sum(ismember(A,B))*find(ismember(A,B))
%or
sol=sum(ismember(A,B)).*find(ismember(A,B))

but none of them is correct. I hope somebody coud help me

Answer 1

Geoff Hayes 2020-4-10

gabriele - try multiplying the result of ismember with a row array of [1 2 3] like

>> sol = [1:size(A,2)] * ismember(A,7);
>> sol
sol =
     1     3     0

thank you a lot. it was pretty easy