[R] SQL/R

[Allan Engelhardt]

There are so many ways....  Here is one:

aggregate(v ~ u, data=X, function(...) length(unique(...)))
#    u v
# 1 T1 2
# 2 T2 1

Hope this helps

Allan.

On 22/07/10 12:52, Gildas Mazo wrote:
> Dear R users,
>
> I want to aggregate data in the following way:
>
> ###
>
> X<- data.frame(u = c("T1","T1","T1","T2"), v=c("a","a","b","a"))
> X
> library(sqldf)
> sqlOut<- sqldf("select count(distinct(v)) from X group by u")
> sqlOut
>
> ###
>
> Now I want to get the same result without using SQL. How can I achieve
> that ?
>
> Thanks for your help,
>
> Gildas
>
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