MATLAB: How to summarize a matrix based on unique groups

functionhistogrammatlab functionvector

I have a vector A=[1 2 1 4; 5 3 5 7; 6 1 8 9], the first row represent age group, and the second row represents skill level, and the third row is the count of people. From A, I want to produce matrix B where is the compact form of A, in other words, if two or more columns represent the people in the same age and skill level group, we remove all of them and only keep one of them. For our example, A([1 2],1) = A([1 2],3) = [1;5], therefore B=[1 2 4; 5 3 7; 14 1 9].

Best Answer

Try this:
A=[1 2 1 4; 5 3 5 7; 6 1 8 9];
[Au, ~, ic] = unique(A([1 2],:)', 'rows');          % Unique Columns
R3 = accumarray(ic, A(3,:));                        % Sum Similar Elements In Row #3
B = [Au R3]'                                        % Desired Result
B =
     1     2     4
     5     3     7
    14     1     9
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