[R] question on isoMDS
hellik at web.de
Mon Apr 12 14:21:10 CEST 2004
I have a question on isoMDS.
My data set (of vegetation) with 210 samples is in this way:
Rotfoehrenau Lavendelweidenau Silberweidenau ....
067_Breg.7 0 2 0 ....
071_Dona.4 0 2 6 ....
I want to do an isoMDS-analysis with the dissimilarity index "bray/curtis"
as discribed in the help-files of the package vegan:
mds.test <- isoMDS(test.bc, initMDS(test.bc), maxit=200, trace=FALSE, tol=1e-7)
Then I get following error message:
"Error in isoMDS(test.bc, initMDS(test.bc), maxit = 200, trace = FALSE, :
zero or negative distance between objects 19 and 20"
The objects 19 and 20 have the same variables in the same way and therefore
they have a zero distance.
My question is: Is it possible to perform an isoMDS with a data set where
some samples have the same variables in the same way?
with greetings from Tyrol
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