# Re: [R] distance in the function kmeans

From: Uwe Ligges (ligges@statistik.uni-dortmund.de)
Date: Fri 28 May 2004 - 19:11:04 EST

```Message-id: <40B70228.7060104@statistik.uni-dortmund.de>

```

n.bouget@laposte.net wrote:

>>n.bouget wrote:
>>
>>
>>>Hi,
>>>I want to know which distance is using in the function kmeans
>>>and if we can change this distance.
>>>Indeed, in the function pam, we can put a distance matrix in
>>>parameter (by the line "pam<-pam(dist(matrixdata),k=7)" ) but
>>>we can't do it in the function kmeans, we have to put the
>>>matrix of data directly ...
>
> Yes but how can we choose the distance to calculate centers?

Ah, you are going to use different distance measure (e.g. euclidean,
manhattan, ...) as in other cluster methods? Well, that's not possible
with the kmeans() implementation. See ?kmeans which tells you:

The data given by x is clustered by the k-means algorithm. When this
terminates, all cluster centres are at the mean of their Voronoi sets
(the set of data points which are nearest to the cluster centre).

The algorithm of Hartigan and Wong (1979) is used.

Of course, you can do some projection based on the calculation of
distances, but I don't think there are functions available to do that
completely automatical - and interpretation of results won't be that
easy ...

Uwe Ligges

>
>>>Nicolas BOUGET
>>
>>As the name says, kmeans() calculates *means* (centres) of
>
> clusters. It
>
>>does not any make sense to do that on distances ...
>>
>>Uwe Ligges
>>
>>
>>
>>>Accédez au courrier électronique de La Poste :
>
> www.laposte.net ;
>
>>>3615 LAPOSTENET (0,34€/mn) ; tél : 08 92 68 13 50 (0,34€/mn)
>>>
>>>______________________________________________
>>>R-help@stat.math.ethz.ch mailing list
>>>https://www.stat.
>
> math.ethz.ch/mailman/listinfo/r-help
>
>
> http://www.R-project.org/posting-guide.html
>
>>
>
> Accédez au courrier électronique de La Poste : www.laposte.net ;
> 3615 LAPOSTENET (0,34€/mn) ; tél : 08 92 68 13 50 (0,34€/mn)
>
>
>

______________________________________________
R-help@stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help