[R] Simple order() data frame question.

[John Kane]

Clearly, I don't understand what order() is doing and as ususl the help for order seems to only confuse me more. For some reason I just don't follow the examples there. I must be missing something about the data frame sort there but what?

I originally wanted to  reverse-order my data frame df1 (see below) by aa (a factor) but since this was not working I decided to simplify and order by bb to see what was haqppening!!

I'm obviously doing something stupid but what? 

(df1 <- data.frame(aa=letters[1:10],
     bb=rnorm(10)))
# Order in acending order by bb
(df1[order(df1[,2]),] ) # seems to work fine

# Order in decending order by bb.
(df1[order(df1[,-2]),])  # does not seem to work


===============================================================
 sessionInfo()
R version 2.13.0 (2011-04-13)
Platform: i386-pc-mingw32/i386 (32-bit)

locale:
[1] LC_COLLATE=English_Canada.1252  LC_CTYPE=English_Canada.1252    LC_MONETARY=English_Canada.1252
[4] LC_NUMERIC=C                    LC_TIME=English_Canada.1252    

attached base packages:
 [1] grid      grDevices datasets  splines   graphics  stats     tcltk     utils     methods   base     

other attached packages:
[1] ggplot2_0.8.9   proto_0.3-9.2   reshape_0.8.4   plyr_1.5.2      svSocket_0.9-51 TinnR_1.0.3     R2HTML_2.2     
[8] Hmisc_3.8-3     survival_2.36-9

loaded via a namespace (and not attached):
[1] cluster_1.13.3  lattice_0.19-26 svMisc_0.9-61   tools_2.13.0   
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