[R] tapply and empty subsets
GPetris at uark.edu
Tue May 14 18:59:15 CEST 2002
I am using tapply to compute means by group, as in
> tapply(y, z, mean)
1 2 3
21.00757 20.50031 NA
where y is a vector and z a factor with levels 1:3.
I would like to get a zero instead of the NA I get when a subset is
empty. The problem is that FUN is not applied to empty cells of the
ragged array. (Of course I am willing to define a function my.mean
that returns 0 for empty vectors)
Does anybody have a suggestion for an easy/fast/elegant workaround?
Thanks in advance,
[ Giovanni Petris GPetris at uark.edu ]
[ Department of Mathematical Sciences ]
[ University of Arkansas - Fayetteville, AR 72701 ]
[ Ph: (479) 575-6324, 575-8630 (fax) ]
[ http://definetti.uark.edu/~gpetris/ ]
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