[R] subset

[Guenther, Cameron]

Marc, 
I have tried unique but unique looks at the entire row.  I have a data
set with a variable TRIPID.  The dataset has 469,000 rows.  In most
cases TRIPID is a unique value.  However, in some cases I have the same
TRIPID value but different values for other variables.  What this
amounts to is an data entry error.  I need to get rid of the repeated
rows that have the same TRIPID but different co-variables.  
Thanks for your help.
Cam 


Cameron Guenther, Ph.D. 
Associate Research Scientist
FWC/FWRI, Marine Fisheries Research
100 8th Avenue S.E.
St. Petersburg, FL 33701
(727)896-8626 Ext. 4305
cameron.guenther at myfwc.com
-----Original Message-----
From: Marc Schwartz (via MN) [mailto:mschwartz at mn.rr.com] 
Sent: Tuesday, May 16, 2006 2:50 PM
To: Guenther, Cameron
Cc: r-help at stat.math.ethz.ch
Subject: Re: [R] subset

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