plyr and table question

On Fri, Apr 3, 2009 at 8:43 AM, baptiste auguie <ba208 at exeter.ac.uk>  
wrote:

That makes sense, so I can do something like,

count <- function(x){
       as.integer(unclass(table(x)))
}

count(d$user_id)

ddply(d, .(user_id), transform, count = count(user_id))

 user_id  website time count
1      20   google  930     2
2      20 facebook 1000     2
3      21    yahoo  935     1
4      25 facebook 1015     1
5      61   google  940     1

Have I missed a built-in function to obtain this result?

ddply(d, .(user_id), transform, count = nrow)

?

Hadley

-- 
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