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Old 03-17-2013, 05:29 PM
boulis boulis is offline
Join Date: Feb 2013
Location: Sydney, Australia
Posts: 29
Default Re: on the right track?

Thanks heer2351 and Sendai. Indeed there are 6 different centre-configurations, the ones you gave complete the picture. You can also see this with paper&pencil.

Originally Posted by heer2351 View Post

What values for Ein do you get when running your algorithm with Lloyds centers?
I think I am still somewhere off the track
With this 4-point example the only options for Ein are: 0, 0.25, 0.5
Anything else you get, you know your code has a bug.

I have not tried it with my code, but Sendai's results seem correct. So you should get Ein =0 for the centres that have 1/3 or 2/3 in them (when the clusters are 3-1 points) and Ein = 0.5 when the centres have 1/2 in them (the case were the clusters are 2-2points)

I also think that it might be impossible to get Ein= 0.25 for any centre configuration, providing that the weights are chosen optimally (i.e., using the pseudo inverse method). So you either make no mistakes, or 2 points are misclassified.
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