Arrange average in same vector values

I want to find the 1-column average of vectors with the same 2 columns values.

At now, D1 vector array is obtained through my function as shown in the figure, and E1 is obtained in ascending order through indexing.

How can I arrange the average values according to the 2 column values of E1 as shown in the figure?

[a,index1]=sort(D1(:,3));
E1=D1(index1(1:1:end,:),:);
[rowE1,colE1]=size(E1);

Answer 1

[Mathieu NOE]

hello

try this

%% dummy data
B = ([1 1 1 1 2 2 2 4 4 4 4 1 1 1 1 2]/8)'; % 2nd column data
A = 100*rand(size(B))';                     % first column data

%% main code
Bu = unique(B);
for ci = 1:numel(Bu)
    ind = (B == Bu(ci));
    A_extract_mean(ci,1) = mean(A(ind));
end

C = [A_extract_mean Bu] % First colums contains average values according to the 2nd column values of E1

[Daeyeon Koh]

It successfully works! thanks a lot.

[Mathieu NOE]

My pleasure (as always) !