Hello all,
I wish to compute site scores using PCA (prcomp) on a matrix with
missing values, for example:
Drain Slope OrgL
a 4 1 NA
b 2.5 39 6
c 6 8 45
d 3 9 12
e 3 16 4
...
Where a,b... are sites.
The command
> pca<-prcomp(~ Drain + Slope + OrgL, data = t, center = TRUE, scale =
TRUE, na.action=na.exclude)
works great, and from
> pca$x
I can get site scores, e.g.
PC1 PC2 PC3
a NA NA NA
b -2.10475208 -2.315128625 -0.885197753
c 5.01177388 -1.778786252 -0.193285051
d 0.28638602 0.298315086 0.386113799
e -0.58861254 0.089498632 -0.434951813
...
Easy enough...
But how do I use the "napredict" argument? Is it intended as an argument
to be used in the prcomp line (as suggested in ?prcomp), or is it to be
used by itself, to replace NAs in the above site score matrix (which is
what I really want to do).
Thank you,
Alain
--
Alain Paquette, Ph.D.
alain.paque...@gmail.com
Centre d'étude de la forêt (CEF)
Université du Québec à Montréal
www.cef-cfr.ca
Projet TRIADE
www.projettriade.ca
alain.paque...@projettriade.ca
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