How to K-means Cluster?

Hi, I have a 732x29 matrix and I would like to cluster the data using kmeasn clustering. The matrix has two clusters (2 classes) that are either 1 or 2 and the 1 or 2 is in the 27th column f the matrix. Here is what I have so far:

fid=fopen('all_classes_withns_dmjd.txt');
myimport=textscan(fid,'%s %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f','Headerlines',1);
fclose(fid);
X=cell2mat(myimport(:,2:29));

This works and it imports the code. What do I do to cluster it? I selected the classes like so:

mydata(1:1016,:);
X= mydata(1:1016,1);
Y= mydata(1:1016,2);
scatter(X,Y)

But I think there is a better way, because this way, MATLAB will not automatically make the data 2 clusters.

I tried the code in the website like so, but it does not work! Why?

fid=fopen('all_classes_withns_dmjd.txt');
myimport=textscan(fid,'%s %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f','Headerlines',1);
fclose(fid);
X=cell2mat(myimport(:,2:29));
opts = statset('Display','final');

[idx,C] = kmeans(X,2,...
                    'Distance','city',...
                    'Replicates',5,...
                    'Options',opts);
plot(X(idx==1,1),X(idx==1,2),'r.','MarkerSize',12)
hold on
plot(X(idx==2,1),X(idx==2,2),'b.','MarkerSize',12)
plot(C(:,1),C(:,2),'kx',...
     'MarkerSize',12,'LineWidth',2)
plot(C(:,1),C(:,2),'ko',...
     'MarkerSize',12,'LineWidth',2)
legend('Cluster 1','Cluster 2','Centroids',...
       'Location','NW')

Thanks!

[Z]

I also tried removing the centers like so:

IDX = kmeans(X,2);

plot(X(idx==1,1),X(idx==1,2),'r.','MarkerSize',12)
hold on
plot(X(idx==2,1),X(idx==2,2),'b.','MarkerSize',12)

legend('Cluster 1','Cluster 2','Centroids',...
       'Location','NW')

And there is an error with the first line

[Walter Roberson]

What happens instead of it working?

[Z]

I get this instead:

kmeans
Attempt to execute SCRIPT kmeans as a function:
C:\Users\Ziba\Documents\MATLAB\caltech\kmeans.m

Error in kmeanscentroid (line 8)
[idx,ctrs] = kmeans(X,2,...

[Kristofer Kusano]

That file (C:\Users\Ziba\Documents\MATLAB\caltech\kmeans.m) is on your matlab path and it is getting called instead of the matlab "kmeans" function. Rename the kmeans.m file in the folder to something else.

[Z]

Thanks for telling me! But I get the same error... This particular line of code:

IDX= kmeans (X,2) OR idx kmeans (X,2)

are always giving me errors no matter how much I play around with them.

[Walter Roberson]

At the MATLAB command prompt use the command

which kmeans

If it gives you a result which is not under a MATLAB toolbox directory then the kmeans that it finds is interfering with the toolbox kmeans and you must rename the kmeans that it does find.

Note: kmeans is part of the Statistics toolbox so you must have that installed and licensed.

Answer 1

[Z]

The reason why the code was not working was the way I plotted it. Come on guys.

[Ade Aulya]

how did you plot it so you could get the answer ?