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x-means k max

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Regular Contributor

x-means k max

Hello friends of the community. a query
I'am trying to apply x-means algorithm for clusterizar some data, the issue is that when I select the operator "x-means" has the parameters k and k min = 2 max = 60
The problem is that it does not let me select a k max below 60. this is a restrigcion algorithm or a bug?
regards
6 REPLIES
Super Contributor

Re: x-means k max

At a first glance this looks like a bug. I will create an internal ticket requesting to investigate this issue.

Best regards,
Marius
Highlighted
Elite

Re: x-means k max

[ Edited ]

It seems you still the same issue, I'm also not able to select anything but 60

 

It works if you add it as a parameter directly in the xml (eg <parameter key="k_max" value="20"/>), looks like this is not added by default 

Elite II

Re: x-means k max

@kayman I do not think this is necessarily a bug---based on parameter description, it simply is the minimum value that is accepted as the maximum range for x-means.  

k max (optional)
The maximal number of clusters which should be detected.
Type: integer
Range: 60 - +∞
Default: 60

 

It looks like the algorthim is still testing every value between 2 (default minimum) and 60 so I am not sure if it matters if you would prefer a smaller maximum, since it would be within your range.

Brian T., Lindon Ventures - www.lindonventures.com
Analytics Consulting by Certified RapidMiner Analysts
Elite

Re: x-means k max

I see, didn't notice that to be honnest...

60 seems however like a fairly big number, the problem is that in my specific case the best value is typically below 20, and therefore it takes like 3 times the necessary amount of time to get the best prediction. In itself not such a big deal but when working with larger datasets it does make a nice difference.

 

Any reason why 60 is chosen, is there a statistical story behind that number (pure out of interest) ?

RMStaff

Re: x-means k max

Hi,

i've read the source code and there is no comment on why 60 is the min.. The class cites the paper: https://www.cs.cmu.edu/~dpelleg/download/xmeans.pdf for the implementation. Not sure if there is some argument in this one.

 

I will open up a ticket internally. If you desperatly need it you can extend the class and change the setting.

 

Best,

Martin

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Head of Data Science Services at RapidMiner
Moderator

Re: x-means k max

Hi,

 

RapidMiner Studio 7.5 will reduce the selectable minimum to 3.

 

Regards,

Marco

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Team Lead Software Engineering | RapidMiner GmbH