[R] help with the unique function

Erik Iverson iverson at biostat.wisc.edu
Wed May 7 18:31:23 CEST 2008


ravi -

This may get you started

count.reps <- function(df) {
   hash  <- do.call("paste", c(df, sep = "\r"))
   cbind(unique(df), Freq = unclass(table(hash)))
}

test <- data.frame(a = rep(1:10, 2), b = rep(1:10, 2))
count.reps(test)

Best,
Erik Iverson

ravi wrote:
> Hi,
> The unique function is easy to understand and use. Beyond that, I want to get also the frequency of repetition of each individual row in a data frame
> Let me explain with an example :
> x<-data.frame(a=c(1,2,3,1,2),b=c(2,3,4,2,3),c=c(10,20,30,10,20))
> xu<-unique(x)
> We have,
>> x
>   a b  c
> 1 1 2 10
> 2 2 3 20
> 3 3 4 30
> 4 1 2 10
> 5 2 3 20
>> xu
>   a b  c
> 1 1 2 10
> 2 2 3 20
> 3 3 4 30
> 
> I want to get the following data frame :
>   a b  c    Freq
> 1 1 2 10    2
> 2 2 3 20    2
> 3 3 4 30    1
> That is, in addition to the unique rows, I want to get the frequency of repetion of each individual row.
> I will appreciate all the help that I can get.
> Thank You,
> Ravi
> 
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