Stavros Macrakis wrote:
> On Tue, Jun 16, 2009 at 5:16 AM, Stefan Uhmann <stefan.uhm...@googlemail.com
>
>> wrote:
>>
>
>
>> why does this not work?
>>
>> df <- data.frame(var1 = c(3,2,1), var2 = c(6,5,4), var3 = c(9,8,7),
>> fac = c('A', 'A', 'B'))
>> tapply(cbind(df$var1, df$var2, df$var3), df$fac, mean)
>>
>>
>
> Because tapply is defined for atomic vectors and not for data frames.
that's not it -- the error message is about lengths. cbind produces a
matrix, and tapply receives no data frame as input. the input is of
correct type, but the lengths do not match -- the length of a 3x3 matrix
is 9.
> Why?
> I don't know.
>
who does? anyway, tapply does "work" for data frames, though it
contradicts the documentation.
vQ
______________________________________________
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.
