[R] tapply and empty subsets

[Giovanni Petris]

I guess for my purpose the following will do.

> x <- tapply(y, z, mean)
> x[is.na(x)] <- 0

Thanks,
Giovanni

> Date: Tue, 14 May 2002 11:59:15 -0500 (CDT)
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> 
> 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
> 
> -- 
> 
>  __________________________________________________
> [                                                  ]
> [ 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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-- 

 __________________________________________________
[                                                  ]
[ 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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