I believe you are misunderstanding what a barchart is (or maybe I do, since I never use 'em). I believe that there should be one quant value for each tclass and stream, and you have several.
?panel.barchart is the place to look for documentation for details of any lattice display. Note especially the "horizontal" argument details (also in ?barchart). You may also wish to consider ?bwplot instead. -- Bert On Tue, Oct 23, 2012 at 2:59 PM, Rich Shepard <rshep...@appl-ecosys.com> wrote: > I've a data frame with this structure: > > 'data.frame': 1987 obs. of 11 variables: > $ site : Factor w/ 24 levels "B(W)","BC-1",..: 1 1 2 2 2 1 1 1 ... > $ sampdate : Date, format: "2000-07-18" "2000-07-18" ... > $ tclass : Factor w/ 8 levels "Annelida","Arachnida",..: 1 5 5 5 5 > ... > $ torder : Factor w/ 18 levels "Achtinedida",..: 13 5 5 10 13 5 7 ... > $ tfamily : Factor w/ 81 levels "","Ameletidae",..: 79 46 46 14 42 ... > $ tgenus : Factor w/ 206 levels "","Acentrella",..: 1 10 10 1 140 ... > $ tspecies : Factor w/ 60 levels "","aequalis",..: 1 1 1 1 1 1 1 ... > $ quant : int 22 527 22 22 11 97 333 11 108 11 ... > $ stream : Factor w/ 7 levels "BCrk","JCrk",..: 1 1 1 1 1 1 1 1 ... > $ basin : Factor w/ 2 levels "H","O": 2 2 2 2 2 2 2 2 2 2 ... > > When I create a bar chart for tclass by stream the resulting bars appear > to have multiple segments (see attached pdf) from this command: > > barchart(quant ~ tclass | stream, data = benthos, main = 'Taxonomic > Classes', xlab = 'Class Name', ylab = 'Number/square meter', scales = list(x > = list(rot = 90))) > > and I want to understand what the segments represent. I thought the formula > 'quant ~ tclass' would produce one bar per class. I cannot find the answer > in the ?barchart help page (it may be there and I'm not seeing it) or the > Lattice book. Your help in increasing my understanding is appreciated. > > TIA, > > Rich > ______________________________________________ > 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. > -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
