[Rd] by "infelicity"

[Tobias Verbeke]

Dear list,

Please find below an example of odd
behaviour of the by function. 

It occurs both under GNU/Linux R 2.6.2
and Windows R 2.7.0alpha. Respective
sessionInfo()'s are given below.

I hope I do not overlook anything.

testFactor <- factor(sample(LETTERS[1:6], size = 42, replace = TRUE))
testMatrix <- matrix(rnorm(42 * 6), nrow = 42)
testDf <- as.data.frame(testMatrix)

by(data = testDf, INDICES = testFactor, FUN = mean) # OK
by(data = testDf, INDICES = testFactor, FUN = median) # error
# Error in median.default(data[x, ], ...) : need numeric data

Kind regards,
Tobias

### GNU/Linux ###
> sessionInfo() 
R version 2.6.2 (2008-02-08) 
i486-pc-linux-gnu 

locale:
LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=en_US.UTF-8;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C

attached base packages:
[1] tools     stats     graphics  grDevices utils     datasets  methods  
[8] base     

other attached packages:
[1] Biobase_1.16.3

### Windows ###

> sessionInfo() 
R version 2.7.0 alpha (2008-03-29 r44988) 
i386-pc-mingw32 

locale:
		LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252

attached base packages:
		[1] stats     graphics  grDevices utils     datasets  methods   base     
>