On Mon, Apr 20, 2015 at 12:56 PM, Sonia Amin <soniaam...@gmail.com> wrote: > Sorry Sarah for my basic question: what does "a column was read as factor" > mean?
A factor is one of the basic types of data in R, and in statistics generally, eg M/F or red/white/blue - a predetermined set of categories that may or may not have an order. More relevantly, if there's something wrong in your data, a stray letter or quote mark for instance, that column is no longer numeric, and R will read it as a factor by default, otherwise as character. str(data) which is NOT the same as just typing data, will show you the classes of your columns, among other things. > When I type data , I obtain all the numeric values and the headears I added > (Consommation,Cylindre,Puissance,Poids) If you just look at data directly, you'll see what look like numbers, perhaps, but according to R one or more columns are not actually numbers. That's why you need str(data). Your problem looks like a lack of basic understanding of how R works. Here are a couple of sources that might help you get started: http://www.burns-stat.com/documents/tutorials/impatient-r/ http://cyclismo.org/tutorial/R/ For more help, you should provide at least the output of str(data) to the list, and ideally a reproducible example. Here are some suggestions for creating a good reproducible example: http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example Sarah > Thanks > > > > 2015-04-20 18:40 GMT+02:00 Sarah Goslee <sarah.gos...@gmail.com>: >> >> What is the problem? One or more of your columns was read as factor, as >> >> str(data) >> >> would show you. To avoid this, you can add stringsAsFactors=FALSE to >> the read.table command, but if you expect your data to be entirely >> numeric then there's something wrong with it that you need to hunt >> down. >> >> Sarah >> >> On Mon, Apr 20, 2015 at 12:33 PM, Sonia Amin <soniaam...@gmail.com> wrote: >> > Dear All, >> > >> > I have written the following lines: >> > >> > >> > data<-read.table("C:\\Users\\intel\\Documents\\SIIID\\datamultiplereg.txt",header >> > = FALSE, sep = "") >> > colnames(data)<-c("Consommation","Cylindre","Puissance","Poids") >> > result.model1<-lm(Consommation~Cylindre+Puissance+Poids, data=data) >> > summary(result.model1) >> > >> > I obtained the following message: >> > >> > >> > Call: >> > lm(formula = Consommation ~ Cylindre + Puissance + Poids, data = data) >> > >> > Residuals: >> > Error in quantile.default(resid) : factors are not allowed >> > In addition: warning message: >> > In Ops.factor(r, 2) : >> > ‘^’ This is not relevant for factors >> > >> > >> > Where is the problem? >> > Thank you in advance >> > >> -- >> Sarah Goslee >> http://www.functionaldiversity.org > > ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.