Find set of values that are unique to the values in another column

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Elian Ricardo Gonzalez Beltran
回答： Stephen23 2019-11-22
I have a matrix like the following.
2 3
2 6
2 8
4 5
5 9
5 39
5 6
I need to do operations on numbers in the second column based on the values in the first column. It should be for the unique vaue "2", mean of (3,6,8) etc. Any help is appreciated. Thanks

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采纳的回答

Erivelton Gualter
Erivelton Gualter 2019-11-22
% Mqtrix
A =[2 3;
2 6
2 8
4 5
5 9
5 39
5 6]
% Get unique values on first collumn
un = unique(A(:,1)); % un = [2 4 5]
% Output
A(A(:,1)==un(1),2)

更多回答（2 个）

Andrei Bobrov
Andrei Bobrov 2019-11-22
[G,d] = findgroups(A(:,1));
out = [d,splitapply(@mean,A(:,2),G)];
Stephen23
Stephen23 2019-11-22
>> M = [2,3;2,6;2,8;4,5;5,9;5,39;5,6]
M =
2 3
2 6
2 8
4 5
5 9
5 39
5 6
>> [U,~,X] = unique(M(:,1));
>> V = accumarray(X,M(:,2),[],@mean);
>> [U,V]
ans =
2.0000 5.6667
4.0000 5.0000
5.0000 18.0000

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