Strange behavior when subsetting data frames with NAs
On Thu, 7 Mar 2002 apjaworski at mmm.com wrote:
I guess I did not expect the change in row names for rows without NAs, that is the change from (1, 3) to (X1, X3) in my zz example.
It tells you this is a new set of row names, not just the old ones repeated.
Andy
__________________________________
Andy Jaworski
Engineering Systems Technology Center
3M Center, 518-1-01
St. Paul, MN 55144-1000
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E-mail: apjaworski at mmm.com
Tel: (651) 733-6092
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Prof Brian D
Ripley To: Andrzej P. Jaworski/US-Corporate/3M/US at 3M-Corporate
<ripley at stats.o cc: r-help at stat.math.ethz.ch
x.ac.uk> Subject: Re: [R] Strange behavior when subsetting data frames with NAs
03/07/2002
01:22 AM
On Wed, 6 Mar 2002 apjaworski at mmm.com wrote:
Here is what I get using R 1.4.1 on Win2k (using precompiled version from
CRAN) and RH 7.2 Linux (compiled form source):
> data.frame(a=c(1, 2, 3, NA, NA), b=c(3, 1, 3, NA, NA)) -> zz
> zz[zz[,2]>2, ]
a b
X1 1 3
X3 3 3
NA NA NA
NA1 NA NA (if there are more
rows with NAs, I get consecutive labels NA2, NA3, ...)
> zz1 <- na.omit(zz)
> zz1[zz1[,2]>2, ]
a b
1 1 3
3 3 3
also
> as.matrix(zz) -> zz
> zz[zz[,2]>2, ]
a b
1 1 3
3 3 3
NA NA NA
NA NA NA
I am not sure if this is bug or a feature, so I am reporting it here.
What exactly do you find strange? It is the correct behaviour and
replicates that of S. Remember that data frames have to have unique row
names, and you asked for rows
zz[,2]>2
[1] TRUE FALSE TRUE NA NA
so new row names have to be created. Matrices do not have to have unique
dimnames.
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._