[R] subset

[Marc Schwartz (via MN)]

On Tue, 2006-05-16 at 14:37 -0400, Guenther, Cameron wrote:
> Hello everyone,
> 
> I have a large dataset (x) with some rows that have duplicate variables
> that I would like to remove.  I find which rows are the duplicates with
> X1<-which(duplicated(x)).  That gives me the rows with duplicated
> variables.  Now, how can I remove just those rose from the original data
> frame.  I think I can create a new data frame without the duplicates
> using subset.  I have tried:
> Subset(x,!x1) and subset(x,!x[x1,])
> I can't seem to find the correct syntax.  Any advice.
> Thanks in advance

Even easier would be to use unique():

  NewDF < unique(x)

NewDF will contain rows from 'x' with duplicates removed.

See ?unique for more information.

unique(), which has a data.frame method, is basically:

  x[!duplicated(x), , drop = FALSE]

which covers the case where the result may contain a single row and
which remains a data frame.

Note that the above presumes that you want to test all columns in 'x'
for dups.

HTH,

Marc Schwartz