Dear Ronaldo,
You were almost there!  Here is a suggestion:

 with(test, tapply(var3, var2, length))
# a b c d e
# 2 1 1 1 1

HTH,
Jorge


2009/9/1 Ronaldo Reis Júnior <>

> Hi,
>
> this is a simple question
>
> I have this data.frame:
>
> > test <-
>
> data.frame(var1=c(1,1,1,1,1,1),var2=c("a","a","b","c","d","e"),var3=c("a1","a1","b1","a1","c1","d1"))
> > test
>  var1 var2 var3
> 1    1    a   a1
> 2    1    a   a1
> 3    1    b   b1
> 4    1    c   a1
> 5    1    d   c1
> 6    1    e   d1
>
> Then I need to calculate the number of var3 excluding the repeated measure
> of
> var2.
>
> With tapply I have this:
>
> > tapply(test$var1,test$var3,sum)
> a1 b1 c1 d1
>  3  1  1  1
>
> But the correct result is:
>
> a1 b1 c1 d1
>  2  1  1  1
>
> because on factor "a1" in var3 I have 2 repeated factor "a" in var2.
>
> I try a simple solution for it but without success. aggregate function dont
> work with factors (var3 by var1).
>
> Anybody have an idea?
>
> Thanks
> Ronaldo
> --
> "It's men like him that give the Y chromosome a bad name."
> --
> > Prof. Ronaldo Reis Júnior
> |  .''`. UNIMONTES/DBG/Lab. Ecologia Comportamental e Computacional
> | : :'  : Campus Universitário Prof. Darcy Ribeiro, Vila Mauricéia
> | `. `'` CP: 126, CEP: 39401-089, Montes Claros - MG - Brasil
> |   `- Fone: (38) 3229-8192 | ronaldo.reis@unimontes.br |
> chrysopa@gmail.com
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