Keeping track of the Index while using "cell2mat" function

4 views (last 30 days)
hey guys, I have a Cell Array a and am using cell2mat function for further clustering analysis, lets say:
a = {[1 2 3; 7 8 9], [4 5 6;10 11 12; 13 14 15]};
b = cell2mat(a(:));
rng(2)
k=2;
[idx] = kmeans(b,k);
which_in_cluster = cell(k,1);
for j = 1:k
which_in_cluster{j} = find(idx == j);
end
Cluster_1 = b(which_in_cluster{1,1},:); % 1st Cluster
Cluster_2 = b(which_in_cluster{2,1},:); % 2nd Cluster
Cluster_1 =
7 8 9
10 11 12
13 14 15
Cluster_2 =
1 2 3
4 5 6
I am now looking for a way to know in which Cell number and row these clusters have originally been in a. So in this example:
Cluster_1 =
7 8 9 % This has been in Cell number 1, row index 2 of a
10 11 12 % This has been in Cell number 2, row index 2 of a
13 14 15 % This has been in Cell number 2, row index 3 of a
Any help is greatly appreciated.
  1 Comment
Ko Fa
Ko Fa on 16 Jan 2021
If anyone got an idea or can send me to the right direction, I'd really appreciate that.

Sign in to comment.

Accepted Answer

Walter Roberson
Walter Roberson on 16 Jan 2021
key = cell2mat((arrayfun(@(IDX) [repmat(IDX, size(a{IDX},1), 1), (1:size(a{IDX},1).']) , 1:numel(a), 'uniform', 0));
Now index rows of key by the cluster number to get the cell number and row number.
  7 Comments
Walter Roberson
Walter Roberson on 17 Jan 2021
F = arrayfun(@(R) f{IDX2(R,1)}(IDX2(R,2)), (1:size(IDX2,1).'))
This is probably one of the cases where it is just clearer to write a loop, and probably more efficient:
nrow = size(IDX2,1);
F = zeros(nrow,1);
for K = 1 : nrow
F(K) = f{IDX2(K,1)}(IDX2(K,2));
end

Sign in to comment.

More Answers (0)

Categories

Find more on Data Type Conversion in Help Center and File Exchange

Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!