They aren't quite lists --- they are actually data.frame()s which are a special sort of list with rownames and other nice things.
To your immediate question, I think you're looking for the formula interface: boxplot(Value ~ State.Fips, data = CB_un) The data= argument is important so boxplot knows where to look for "Value" and "State.Fips" Best, Michael On Mon, Jun 11, 2012 at 11:29 AM, Samantha Sifleet <[email protected]> wrote: > Hi, > > I am a relatively new to R. So, this is probably a really basic issue that > I keep hitting. > > I read my data into R using the read.csv command: > > x = rep("numeric", 3) > CB_un=read.csv("Corn_Belt_unirr.csv", header=TRUE, colClasses=c("factor", > x)) > > # I have clearly told R that I have one factor variable and 3 numeric > variables in this table. > #but if I try to do anything with them, I get an error > > boxplot(CB_un["Value"]~CB_un["State.Fips"]) > > Error in model.frame.default(formula = CB_un["Value"] ~ > CB_un["State.Fips"]) : > invalid type (list) for variable 'CB_un["Value"]' > > # Because these variables are all stored as lists. > #So, I have to unpack them. > > CB_unirr_rent<-as.numeric(unlist(CB_un["Value"])) > CB_unirr_State<-as.factor(unlist(CB_un["State.Fips"])) > > #before I can do anything with them > > boxplot(CB_unirr_rent~CB_unirr_State) > > Is there a reason my data is always imported as lists? Is there a way to > skip this upacking step? > > Thanks, > > Sam > [[alternative HTML version deleted]] > > ______________________________________________ > [email protected] 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. ______________________________________________ [email protected] 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.
