Count the occurence certain elements based on condition in next column

Hello.

I have a matrix consists of A = [ 1 3 2 2 4 1 2 3 4 1 3] and B = [0 0 -3 0 2 1 4 0 0 -2 0]

How can I determine the occurence of element in A when corresponding value in B is not 0:

C = [

1 2

2 2

3 0

4 1]

Please help me..

Really appreciate it!!

Answer 1

[Bruno Luong]

U=unique(A(:));
[~,J]=ismember(A(B~=0),U);
n=accumarray(J(:),1,size(U));
C=[U,n]

[Daniar Fahmi]

Thanks.. It also works!!!

Answer 2

[Ameer Hamza]

Try this

A = [1 3 2 2 4 1 2 3 4 1 3];
B = [0 0 -3 0 2 1 4 0 0 -2 0];

C = [1:max(A); histcounts(A(B~=0), 'BinMethod', 'integers')].'

[Daniar Fahmi]

Woww.. Thank you very much. Exactly what I need!!

[Ameer Hamza]

I am glad to be of help!!!

[Daniar Fahmi]

Hi..

Is there any limitation for histcounts function? because when I used it in larger data (near 2 x 60M) and then it was found that unique element (vector A) was 360 data, the result of histcounts was only 300 data

[Ameer Hamza]

Can you share your data in a .mat file?

[Daniar Fahmi]

here is my data

[Ameer Hamza]

Following solution will be more robust

A = dataPD(1,:);
B = dataPD(2,:);

C = [1:max(A); histcounts(A(B~=0), 0.5:1:max(A)+0.5)].'

[Daniar Fahmi]

thanks.. It works!!!

[Bruno Luong]

Attention A of your data contains 82335 0s and they are discarded from counting

[Daniar Fahmi]

Yeah. I have just realised it..