Grouping and doing mean

Grouping and doing mean.matlab

% based on http://stackoverflow.com/questions/22792020/matlab-accumarray-weighted-mean
data = [10 1;30 1;20 2;30 1;20 4;20 6]

%{

data =

    10     1
    30     1
    20     2
    30     1
    20     4
    20     6    
%}

data = sortrows(data, 1);
Vals = data(:,2);
[ID, ~, Groups] = unique(data(:,1),'stable')
%{
ID =

    10
    20
    30


Groups =

     1
     2
     2
     2
     3
     3
%}
fnMean = @(ii) mean(Vals(ii));
means = accumarray(Groups, 1:numel(Groups), [], fnMean)

%{
means =

     1
     4
     1
%}