# [R] Number of replications of a term

Laetitia Marisa Laetitia.Marisa at cgm.cnrs-gif.fr
Tue Jan 24 18:05:48 CET 2006

```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 )

Of course I have a vector of more than 40 000 ID and the function I
wrote (it orders my data and checks on ID:Name of the data if the next
term is the same as the previous one (see below) ) is really slow
(30minutes for 44290 terms). But I don't have time by now to write a C
function.
Thanks a lot for your help,

Laetitia.

Here is the function I have written maybe I have done something not
optimized :

repVector <- function(obj){

# order IDName
ord <- gif.indexByIDName(obj)
ordobj <- obj[ord,]

nspots <- nrow(obj)
# vector of spot replicates number
spotrep <- rep(NA, nspots )

# function to get ID:Name for a given spot
spotidname <- function(ind){
paste(ordobj\$genes[ind, c("ID","Name") ], collapse=":")
}

spot <- 1

while( spot < nspots ){
i<-1
while( spotidname(spot) == spotidname(spot + i) ){

i <- i + 1
}

spotrep[spot : (spot + i-1)] <- i
spot <- spot + i
#cat("spot : ",spot,"\n")
}

obj\$genes\$spotrep <- spotrep[order(ord)]

obj

}

```