[R] Fwd: MDS problems [ajtee@ajtee.uklinux.net]

[Adam Tee]

Hi all,


I'm trying to perform an MDS of some data that I have.  When I use
cmdscale everything is fine and I get some interesting results however,
the tends to be low.

What I wnat to do is compare this with the Non-Metric MDS using isoMDS  
or sammon. However, when I try using these I get the following message.

Error in isoMDS(x.dist) : zero or negative distance between objects 2  
and 4

I am using as.dist to convert my full dissimilarity matrix.
Some of the dissimilarities, other than the diagonal, are zero which is  
causing this, is there anything I can do to resolve this.


Below is a sample dissimilarity matrix

0       0       0.0694153       0.187033        0.193339
0       0       0.0146605       0.36829 	0.563406
0.0694153       0.0146605       0       	0.347965
0.187033        0.36829 	0.347965        0


Thanks

Adam