[R] mean fn in combination with by() XXXX

[Dan Abner]

 Hi all,

Can anyone please explain the following results (why does median()
work here but not mean())? Is there a fix or work around for this?

Thanks,

Dan


> by(urpdata[,2],urpdata[,12],mean,na.rm=TRUE)
Error in FUN(X[[1L]], ...) : could not find function "FUN"
> by(urpdata[,2],urpdata[,12],median,na.rm=TRUE)
urpdata[, 12]: post
[1] 64
------------------------------------------------------------------------------------------------------------------------------------
urpdata[, 12]: pre
[1] 83