[R] loess parameters

[Thomas Jagoe]

Hi,
I have been successfully using the loess function for normalisation of a 2D
array set.
We have recently improved the quality criteria for the data and the numbers
of data points has been reduced to around from around 1000 to 700.
Previously the following would return the loess normalised values for
array$logratio but I am now getting an error:

> array <- read.table("A1.txt", header=T, sep="\t")
> array$logratio<-array$logs555-array$logs647
> array$logav<-(array$logs555+array$logs647)/2
> library(modreg)
> loess2d<-loess(logratio~x+y,data=array)
> array$logratio2DLoeNorm <-array$logratio - predict(loess2d, array)
Error in vector("double", length) : negative length vectors are not allowed

I am assuming that this is due to a problem fitting the data at some
locations and I have tried altering span without much success.  Can anyone
please advise ?

With thanks

Thomas