Thanks Bill and William. Both solutions work, and both have introduced me
to whole new R functions which I'm still wrapping my head around.
What a great resource this list is.
Thanks again,
Rob
------------------------------------------
Robert W. Baer, Ph.D.
Professor of Physiology
Kirksville College of Osteopathic Medicine
A. T. Still University of Health Sciences
800 W. Jefferson St.
Kirksville, MO 63501
660-626-2322
FAX 660-626-2965
--------------------------------------------------
From: "William Dunlap" <wdun...@tibco.com>
Sent: Monday, May 09, 2011 5:17 PM
To: "Robert Baer" <rb...@atsu.edu>; <R-help@r-project.org>
Subject: RE: [R] Creating Observation ID
Does the following work for you?
> df2 <- transform(df, ObsID=ave(rep(0,length(Group)), Group,
FUN=seq_along))
> head(df2)
Value Group ObsID
1 -0.0025132 B 1
2 -1.2456156 A 1
3 -2.0531704 B 2
4 1.5861770 B 3
5 0.1900908 A 2
6 0.7197067 B 4
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-----Original Message-----
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of Robert Baer
Sent: Monday, May 09, 2011 2:22 PM
To: R-help@r-project.org
Subject: [R] Creating Observation ID
If I have a data frame something like:
Value=rnorm(30)
Group = sample(c('A','B','C'), 30, replace=TRUE)
df = data.frame(Value, Group)
It seems like it should be simple to create an 'ObsID' column
which indicates the observation order of each Value within
each of the 3 groups. Somehow, I can't quite see how to do
it without manually sub-setting the parent data frame and
then putting it back together again.
Anyone able to get me started on a cleaner (more R-like) approach?
Thanks,
Rob
------------------------------------------
Robert W. Baer, Ph.D.
Professor of Physiology
Kirksville College of Osteopathic Medicine
A. T. Still University of Health Sciences
800 W. Jefferson St.
Kirksville, MO 63501
660-626-2322
FAX 660-626-2965
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
