how to count the number of occurrences of these numbers (with some conditions)

I have A(1,:) = [1, 2, 5, 2 , 1 , 2];

A(2,:) = [0,1,1,0,1,0];

I want to count the unique number of occurences in A(1,:) so this is simply unique(A(1,:)), which will give

[1, 2, 5]

But i want to count/add the number of ones in A(1,:). So I want another output to be this: first element corresponds to the number of 1's for 1. Next, number of 1's for 2, and so on.

[1,1, 1];

How do i do this?

Answer 1

[Bruno Luong]

A(1,:) = [1, 2, 5, 2 , 1 , 2];
A(2,:) = [0,1,1,0,1,0];

[B,~,J] = unique(A(1,:));
N = accumarray(J(:),A(2,:)');
B = B';
table(B,N)

ans = 3×2 table
    B    N
    _    _

    1    1
    2    1
    5    1

Answer 2

[SungJun Cho]

Hi,

The code below should solve your problem.

A(1,:) = [1,2,5,2,1,2];
A(2,:) = [0,1,1,0,1,0];

uA = unique(A(1,:));

answer = zeros(1,length(uA));

for i = 1:length(uA)
    array = A(2,:);
    answer(1,i) = sum(array(A(1,:) == uA(i)));
end

Here, "answer" will give you the output [1,1,1] and "uA" the array [1,2,5].