I think the unique function is superfluous:
> x[x$X1 %in% x$X1[x$X2==1], ]
X1 X2
1 11 0
2 11 0
3 11 0
4 11 1
8 13 0
9 13 1
10 13 1
--
David Winsemius
On Apr 2, 2009, at 12:43 PM, Patrizio Frederic wrote:
or the exactly equivalent form:
x[x$X1 %in% unique(x[x$X2>0,"X1"]), ]
Patrizio
2009/4/2 Nutter, Benjamin <nutt...@ccf.org>:
x <-
data.frame(matrix(c(rep(11,4),rep(12,3),rep(13,3),rep(0,3),
1,rep(0,4),re
p(1,2)),ncol=2))
id.keep <- unique(subset(x,X2>0)$X1)
x2 <- subset(x,X1 %in% id.keep)
x2
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org
]
On Behalf Of Stephan Lindner
Sent: Thursday, April 02, 2009 11:26 AM
To: r-h...@stat.math.ethz.ch
Subject: [R] Selecting all rows of factors which have at least one
positive value?
Dear all,
I'm trying to select from a dataframe all rows which correspond to a
factor (the id variable) for which there exists at least one positive
value of a certain variable. As an example:
x <-
data.frame(matrix(c(rep(11,4),rep(12,3),rep(13,3),rep(0,3),
1,rep(0,4),re
p(1,2)),ncol=2))
x
X1 X2
1 11 0
2 11 0
3 11 0
4 11 1
5 12 0
6 12 0
7 12 0
8 13 0
9 13 1
10 13 1
and I want to select all rows pertaining to factor levels of X1 for
which exists at least one "1" for X2. To be clear, I want rows 1:4
(since there exists at least one observation for X1==11 for which
X2==1) and rows 8:10 (likewise).
It is easy to obtain the corresponding factor levels (i.e.,
unique(x$X1[x$X2==1])), but I got stalled selecting the corresponding
rows. I tried grep, but then I have to loop and concatenate the
resulting vector. Any ideas?
Thanks a lot!
Stephan
--
-----------------------
Stephan Lindner
University of Michigan
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______________________________________________
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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.
______________________________________________
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.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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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.
