[R] Strange behavior when subsetting data frames with NAs

[apjaworski@mmm.com]

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.

Andy

__________________________________
Andy Jaworski
Engineering Systems Technology Center
3M Center, 518-1-01
St. Paul, MN 55144-1000
-----
E-mail: apjaworski at mmm.com
Tel:  (651) 733-6092
Fax:  (651) 736-3122

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