Re: first instance extraction

[David L Lorenz <lorenz@usgs.gov>]

Michael,
  Check the documentation for the
duplicated() function. It will return a vector indicating which entries
are repeats of a previous entry, therefore !duplicated() returns a vector
of the first instance of a value.
Dave

"Michael Slattery" <Michael.Slattery@epa.state.oh.us>
Sent by: s-news-owner@lists.biostat.wustl.edu

10/25/2006 06:05 AM

To	<s-news@wubios.wustl.edu>
cc
Subject	[S] first instance extraction

Hello all, 
I am trying to understand how to extract the first instance
of a dataframe record, in which the index may appear any number of times
(at least once),  into a dataframe which then contains the _first_
record of each index (and subsequent data). The dataframe has mixed data
types, and the index for extraction can either be a factor or a character,
i.e., 
 
index      data1     data2  
 data3
 
char1      ...        
....        ...
char1
char1
char2
char2
char3
char3
char3
char3
char3
char4
 
 
On S-Plus 7.0 Pro, Windows XP Pro
thanks all !!
 
 
Michael W. Slattery
Geologist, Ohio EPA
122 S. Front Street
Lazarus Government Center
Columbus OH 43215
michael.slattery@epa.state.oh.us
614-728-1221 (Ph)
614-644-2909 (Fax)