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 <rshepard at
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 at 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