[R] help! kennard-stone algorithm in soil.spec packages does not work for my dataset!!!

[Leonardo Ramirez-Lopez]

Hi all

Certainly there are some problems with the "ken.sto" function. In addition
there are some considerations that need to be taken into account before
using this code. For instance, it projects the data onto a principal
component space prior sampling. In this case is necessary to check if a PCA
is really necessary. 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 correctly. If some of you still need it just drop me an e-mail.
Regards, 

Leonardo Ramirez-Lopez, 

Researcher
Georges Lemaître Centre for Earth and Climate Research
Earth and Life Institute
Université 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 Tübingen
Rümelinstr. 19-23
72070 Tübingen
Germany
http://www.geographie.uni-tuebingen.de/ 




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