[R] Number of replications of a term
ggrothendieck at gmail.com
Tue Jan 24 19:29:26 CET 2006
Nice. I timed it and its much faster than mine too.
On 1/24/06, Barry Rowlingson <B.Rowlingson at lancaster.ac.uk> wrote:
> Laetitia Marisa wrote:
> > Hello,
> > Is there a simple and fast function that returns a vector of the number
> > of replications for each object of a vector ?
> > For example :
> > I have a vector of IDs :
> > ids <- c( "ID1", "ID2", "ID2", "ID3", "ID3","ID3", "ID5")
> > I want the function returns the following vector where each term is the
> > number of replicates for the given id :
> > c( 1, 2, 2, 3,3,3,1 )
> > table(ids)[ids]
> ID1 ID2 ID2 ID3 ID3 ID3 ID5
> 1 2 2 3 3 3 1
> 'table(ids)' computes the counts, then the subscripting [ids] looks it
> all up.
> Now try it on your 40,000-long vector!
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