R help - Jan 2012 - problems with method ken.sto in package soil.spec: subscript out of bounds

Hi All,

I would like to use Kennard-Stone algorithm for splitting a dataset.
> mydata <-
read.csv(url("http://www.ats.ucla.edu/stat/r/dae/binary.csv
"))
> library("soil.spec")
> ken.sto(mydata,per.n=0.3)
Error in ken.sto(mydata, per.n = 0.3) : subscript out of bounds

I found that other people run into this problem as well:
http://r.789695.n4.nabble.com/help-kennard-stone-algorithm-in-soil-spec-packages-does-not-work-for-my-dataset-td3031344.html

The package maintainers email (Thomas Terhoeven-Urselmans) is apparently
outdated, I already tried to send him an email.
Any help would be very much appreciated,

Best regards,
Martin

-- 
Dipl-Inf. Martin Gütlein
Phone:
+49 (0)761 203 8442 (office)
+49 (0)177 623 9499 (mobile)
Email:
guetlein@informatik.uni-freiburg.de



-- 
Dipl-Inf. Martin Gütlein
Phone:
+49 (0)761 203 8442 (office)
+49 (0)177 623 9499 (mobile)
Email:
guetlein@informatik.uni-freiburg.de

	[[alternative HTML version deleted]]

Hi Martin, 

Certainly there are some problems with the "ken.sto" function.... In
addition there are some considerations that you have to take into account
before using this code. For instance, it projects the data onto a principal
component space prior sampling. In this case you have to a PCA is really
necessary for your data. Second, this function uses the Euclidean distance
(ED) as metric for selecting the samples. By using the ED directly on the
PCs, the PCs with high explained variance will ?dominate? the measurements.
In this case is better to standardize the PCs prior ED computation or use
the Mahalanobis distance.
Whatever, I have modified the ?ken.sto? code and now seems to be that it
works for your data ;-) . If you still need it just drop me an e-mail.
Regards, 

Leonardo Ramirez-Lopez, 

Researcher
Georges Lema?tre Centre for Earth and Climate Research
Earth and Life Institute
Universit? Catholique de Louvain,
3 Place Louis Pasteur
1348, Louvain la Neuve
Belgium
e-mail: leonardo.ramirez at uclouvain.be

http://www.uclouvain.be/en-teclim.html


Ph.D Researcher
Physical Geography and Soil Science
Institute of Geography
University of T?bingen
R?melinstr. 19-23
72070 T?bingen
Germany
http://www.geographie.uni-tuebingen.de/ 



--
View this message in context:
http://r.789695.n4.nabble.com/problems-with-method-ken-sto-in-package-soil-spec-subscript-out-of-bounds-tp4288193p4306689.html
Sent from the R help mailing list archive at Nabble.com.