Find number of clusters remaining after doing agglomerative hierarchical clustering

I used agglomerative hierarchical clustering and stopeed clutering by giving a cutoff value. now I need to get the number of clusters in that particular image in order to proceed. Can someone help me?

Answer 1

[Mann Baidi]

Hi @Parkavi Kabilathas,

I am assuming that you would like to get the number of clusters present in the data after using cutoff value in the agglomerative hierarchical clustering in MATLAB.

You can check the number of clusters in the data by using the code below for reference.

% Sample data
rng default; 
data = randn(50, 2);

% Perform hierarchical clustering
Z = linkage(data, 'ward'); % 'ward' linkage method is used here, but other methods are available


idx = cluster(Z,'cutoff',0.4)

idx = 50x1

19 26 28 4 11 17 23 21 29 15

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histogram(idx) % Plot histogram for the idx

figure;
% Plot data points colored by cluster
gscatter(data(:,1), data(:,2), idx);
hold on;
legend('off')

% Count the number of clusters
num_clusters = max(idx);

fprintf('Number of clusters: %d\n', num_clusters);

Number of clusters: 29

If you would like to know more about these functions we can go throught their documentation, using the following link.

• Linkage: https://www.mathworks.com/help/stats/linkage.html
• Cluster: https://www.mathworks.com/help/stats/cluster.html

Hoping this will help in resloving your query!