Re: [R] kmeans and incom,plete distance matrix concern

From: Christian Hennig <chrish_at_stats.ucl.ac.uk>
Date: Tue 08 Aug 2006 - 00:46:40 EST

First of all, kmeans doesn't work on distance matrices.

On Mon, 7 Aug 2006, Ffenics wrote:

> Hi there
> I have been using R to perform kmeans on a dataset. The data is fed in using read.table and then a matrix (x) is created
>
> i.e:
>
> [
> mat <- matrix(0, nlevels(DF$V1), nlevels(DF$V2),
> dimnames = list(levels(DF$V1), levels(DF$V2)))
> mat[cbind(DF$V1, DF$V2)] <- DF$V3
> This matrix is then taken and a distance matrix (y) created using dist() before performing the kmeans clustering.
>
> My query is this: not all the data for the initial matrix (x) exists and therefore the matrix is not fully populated - empty cells are populated with '0's.
>
> Could someone please tell me how this may affect the result from the dist() command - because a '0' in a distance matrix means that the two variables are identical doesnt it(?) - but I dont want tthings clustered together simply because there was no information.
>
> Is this a problem and are there ways to circumnavigate them? Thanks
>
> [[alternative HTML version deleted]]
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue Aug 08 04:14:58 2006

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