To my knowledge, this has not been reported previously, and doesn't
seem to have been changed in R-devel or R-patched.
If M is a matrix with coloumn names, and
mod <- prcomp(M) # or princomp
then predicting a single observation (row) with predict() gives the
error
Error in scale.default(newdata, object$center, object$scale) :
length of 'center' must equal the number of columns of 'x'
This doesn't happen if M doesn't have coloumn names.
For instance:
> M <- matrix(rnorm(30), ncol = 3)
> mod <- prcomp(M[-1,])
> predict(mod, newdata = M[1,, drop = FALSE])
PC1 PC2 PC3
[1,] -1.666191 -2.333012 -1.424587
> colnames(M) <- 1:3
> mod <- prcomp(M[-1,])
> predict(mod, newdata = M[1,, drop = FALSE])
Error in scale.default(newdata, object$center, object$scale) :
length of 'center' must equal the number of columns of 'x'
I believe the problem is the line
newdata <- newdata[, nm]
in predict.prcomp (line 106 of prcomp.R) and predict.princomp (line 11
of princomp-add.R), which should probably be
newdata <- newdata[, nm, drop = FALSE]
Version:
platform = x86_64-unknown-linux-gnu
arch = x86_64
os = linux-gnu
system = x86_64, linux-gnu
status =
major = 2
minor = 2.0
year = 2005
month = 10
day = 06
svn rev = 35749
language = R
Locale:
LC_CTYPE=no_NO.UTF-8;LC_NUMERIC=C;LC_TIME=no_NO.UTF-8;LC_COLLATE=no_NO.UTF-8;LC_MONETARY=no_NO.UTF-8;LC_MESSAGES=no_NO.UTF-8;LC_PAPER=C;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=C;LC_IDENTIFICATION=C
Search Path:
.GlobalEnv, package:methods, package:stats, package:graphics,
package:grDevices, package:utils, package:datasets, Autoloads, package:base
--
Bjørn-Helge Mevik
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