I think David's idea about NA's was correct. This works: prcomp(na.omit(Chlor1[,-(1:2)]), scale=TRUE)
The number of cases drops from 288 to 250. There also three 0's in the dataset that probably should be NA's. ---------------------------------------------- David L Carlson Texas A&M University College Station, TX 77843-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of David Winsemius Sent: Wednesday, August 17, 2011 5:03 PM To: David Winsemius Cc: r-help@r-project.org; Rosario Garcia Gil Subject: Re: [R] prcomp On Aug 17, 2011, at 5:47 PM, David Winsemius wrote: > > On Aug 17, 2011, at 5:19 PM, Rosario Garcia Gil wrote: > >> Hello >> >> I am trying to run a PCA on the attached file, but I get this error >> message: >> >> pc<-prcomp(data[,-(1:2)],scale=T)$x >> Error in svd(x, nu = 0) : infinite or missing values in 'x' > > What part of "missing values in 'x'" is unclear in that error message? After looking further at the prcomp defaults I see that na.action defaults to na.omit so it may not be the missing data, but rather collinearity. Do these plotting and descriptive steps to see that your data is extremely clustered: matplot(dat[,-(1:2)] ) pairs(dat[-(1:2)]) summary(dat[-(1:2)]) So the effort to invert the data matrix is probably failing due to the application of inappropriate data reduction to variables which, though nominally numeric, are really categorical, and fairly strangely distributed ones at that. Also not this advice in ?prcomp: "Note that scale = TRUE cannot be used if there are zero or constant (for center = TRUE) variables." I cpunt four variables that violate that restriction. But removing scale=T still does not fix the problem. -- David Winsemius, MD West Hartford, CT ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.