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matlabcluster-analysisfuzzy

Matlab output each cluster from fuzzy clustering

How do you output the data from each cluster using FCM in matlab? 

[center,U,obj_fcn] = fcm(data,cluster_n)
Solution

  • I used the U vector to determine which class each datapoint belongs to. It content can be thought of as the probability for each class to belong to a class (notice then all columns sum to 1), so choosing which ever class is most probable is a reasonable approach. This is done by storing the second output argument of max().

    Below I have stated some general purpose code you can use. 

    %# Start parameters and variables
nClasses = 3;
CM = jet(nClasses); %# Colormap for visualization of up to 255 classes

%# Create dataset
data = [mvnrnd([0 0],eye(2),100); mvnrnd([3,3],0.5*eye(2),50)];

%# Cluster
[center,U,obj_fcn] = fcm(data,nClasses); 

%# Extract class assignment
[~,y] = max(U); 

%# Visualize
f1=figure(1);clf
plot(data(:,1),data(:,2),'.k')
hold on
for i = 1 : nClasses
    plot(data(y==i,1),data(y==i,2),'o','color',CM(i,:));
end

    enter image description here

    EDIT:

    To extract the datapoints of one class into a new variable, simply use

    class1data = data(y==1,:);