problem with select.rows

[Joseph LeBouton <lebouton@msu.edu>]

Hello all,

HELP! I'm running S-plus 6.2, but the problem is the same in R 1.8.1.  I 
apparently misunderstand the select.rows command.  Can anybody help me with 
this?
I ran into a problem trying to select rows (of a factor variable) from a 
dataframe and use the selected subset of factors to create summary 
statistics and particularly barcharts. I keep getting barchart labels (and 
summary stats) for factors I excluded using the select.rows 
command.  Values associated with the non-selected factor values are zeros, 
but I want these factor values to disappear altogether from both the 
summary stats and the barcharts!   In the full dataset I want to select 6-8 
species from a total of 39 species.  I've included some sample code that 
replicates my problem.
thanks,

jlb


########
#EXAMPLE CODE THAT REPLICATES PROBLEM:


#Problem with select.rows to exclude observations from a barchart:

#Create dataframe with 4 rows, 2 columns:
r_data.frame(c(1:4))
r_cbind(r, c("apple","apple","bananna","orange"))

#Select rows of dataframe 'r' to work with; exclude "apple" from dataframe.
s_select.rows(r, r[,2]!="apple")

#summarize 'r' and 's'; notice that "apple" still appears in summary of 's',
#  though it occurs zero times in the dataframe.
summary(r)
summary(s)

#Do a bar chart of both dataframes.  Notice that "apple" appears in the
# bar chart of both the 1st and 2nd dataframes, though all occurrences of
# "apple" should have been excluded by the select.rows.
barchart(r[,2]~r[,1])
barchart(s[,2]~s[,1])

************************************************************************
Joseph LeBouton
PhD candidate
Michigan State University
Department of Forestry
East Lansing, Michigan 48824

(517) 355-7744

lebouton@msu.edu