How do I retrieve groupwise leaf nodes with Hierarchical Clustering?

I am using Hierarchical Clustering wants to know how to retrieve the leaf nodes for each cluster groups.

To give you the idea, please refer to the illustration just above the "Dendrograms."

https://www.mathworks.com/help/stats/hierarchical-clustering.html?lang=en

I would like to find:

    Group 6: 4, 5

    Group 7: 1, 3

    Group 8: 1, 3, 4, 5

    (The enclosing group necessarily includes all: 1, 2, 3, 4, 5)

Answer 1

[MathWorks Support Team]

As of MATLAB R2015a, a function for retrieving groupwise leaf nodes with Hierarchical Clustering is not available.

As a workaround consider the following script:

    rng default;  % For reproducibility

    X = [1   2; ...

         2.5 4.5; ...

         2   2; ...

         4   1.5;...

         4   2.5];

    Y = pdist(X);

    Z = linkage(Y);

    dendrogram(Z);

    % A

    n = size(Z,1)+1;

    v = eye(n,n*2-1)>0;

    for i = 1:n-1 

        v(:,i+n) = any(v(:,Z(i,[1 2])),2); 

    end

    v = v(:,n+1:end)

    % B

    [index_row , index_column] = ind2sub(size(v), find(v));

    index_row(index_column == 1).'

    index_row(index_column == 2).'

    index_row(index_column == 3).'