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

Question

cgo 2021-4-23

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https://ww2.mathworks.cn/matlabcentral/answers/810695-how-to-count-the-number-of-occurrences-of-these-numbers-with-some-conditions

回答： Bruno Luong 2021-4-23

采纳的回答： Bruno Luong

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?

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Answer 1

Bruno Luong 2021-4-23

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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

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Answer 2

SungJun Cho 2021-4-23

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https://ww2.mathworks.cn/matlabcentral/answers/810695-how-to-count-the-number-of-occurrences-of-these-numbers-with-some-conditions#answer_682535

编辑：SungJun Cho 2021-4-23

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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