number of count of each unique row

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Hi Louis,

If I am understanding your question correctly, here is one way:
suppose your matrix is M of dimension n x k.

D <- data.frame(M)  # convert to data frame
ones <- rep(1, n)   # a column of 1s

Now you can count the number of repeats of each unique row.

aggregate( ones, by = as.list(D), FUN = sum)

The output will be a data frame with the unique rows, and a column at
the end labeled "x" with the frequency of each unique row.

Once you get this you can convert to a list, manipulate, etc.  I am
sure that there exist faster/better methods.

Best,
Jay
Hi,

I have a matrix of duplicate rows. How to output a list the unique rows with their count? I have used "unique" to have the unique rows, but can't produce the occurences of each unique row.

Thanks

Louis

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Hi,

I have a matrix of duplicate rows. How to output a list the unique rows with their count? I have used "unique" to have the unique rows, but can't produce the occurences of each unique row.

Hi Louis,
If you want the unique rows returned, this might do the job.

unique.rows<-function(x) {
  nrows<-dim(x)[1]
  urows<-1:nrows
  for(i in 1:(nrows-1)) {
   for(j in (i+1):nrows) {
    if(!is.na(urows[j])) if(all(x[i,]==x[j,])) urows[j]<-NA
   }
  }
  return(x[urows[!is.na(urows)],])
}

Jim
i didn't test, but i think you want something like:

table(apply(x, 1, paste, collapse=","))

where "x" is your matrix...

b

Louis Martin wrote:
Hi,

I have a matrix of duplicate rows. How to output a list the unique  
rows with their count? I have used "unique" to have the unique  
rows, but can't produce the occurences of each unique row.

Hi Louis,
If you want the unique rows returned, this might do the job.

unique.rows<-function(x) {
 nrows<-dim(x)[1]
 urows<-1:nrows
 for(i in 1:(nrows-1)) {
  for(j in (i+1):nrows) {
   if(!is.na(urows[j])) if(all(x[i,]==x[j,])) urows[j]<-NA
  }
 }
 return(x[urows[!is.na(urows)],])
}

Jim

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.