# How to check if a column data is equal to any of a group of values?

2 views (last 30 days)
Leon on 3 Oct 2020
Edited: madhan ravi on 3 Oct 2020
I have a column data A like the below:
A = [1; 3; 2; 7; 11; 6];
B can be a group of numbers with unknow counts. For example B can be like the below:
B = [1; 7];
Here is my question. How do I come up with an index to show the elemens of A that can be any of B? For example if I know B has two elements, I can use something like the below, but B can have an unknown number of elements.
Ind1 = A == B(1);
Ind2 = A == B(2);
Ind = Ind1 + Ind2;

Sulaymon Eshkabilov on 3 Oct 2020
Hi,
Ind = sum(Ind1) + (Ind2);
Leon on 3 Oct 2020
Thanks!
Is there a better way to do this? B has an unknown number of elements, not necessarily 2.

Sulaymon Eshkabilov on 3 Oct 2020
You can use a loop for instance if you have many Bs, e.g.:
for ii = 1:numel(B)
Ind = A==B(ii); S(ii) = sum(Ind(:));
end
S_all=sum(S); % Total number of observed cases
##### 2 CommentsShowHide 1 older comment
Sulaymon Eshkabilov on 3 Oct 2020
You have edited the code that I've provide incorrectly.

Sulaymon Eshkabilov on 3 Oct 2020
Altenrative (more efficient one) solution can be this one:
S = sum(sum(ismember(A,B)))

madhan ravi on 3 Oct 2020
Edited: madhan ravi on 3 Oct 2020
clear sum
Ind = sum(ismember(A, B), 2)
%Or perhaps you need
Ind = nnz(ismember(A, B))
%or
fprintf('%d occurs %d times/s\n', [B.'; sum(A == B.')])

R2020b

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