Folks: Problem: [<-.data,frame() is losing attributes under certain curcumstances shown below.
I think this is a bug, at least in documentation, as I was unable to find explicit documentation of the behavior. Indeed, the only documentation I found told me attributes are preserved. Here is a detailed description: > df <- data.frame(a=1:3, b=letters[1:3]) > attr(df,"foo") <- 10 > df a b 1 1 a 2 2 b 3 3 c > attributes(df) $names [1] "a" "b" $row.names [1] 1 2 3 $class [1] "data.frame" $foo [1] 10 ## But now we add a new column using matrix-type indexing > df[,"c"] <- 10:12 > df a b c 1 1 a 10 2 2 b 11 3 3 c 12 > attributes(df) $names [1] "a" "b" "c" $row.names [1] 1 2 3 $class [1] "data.frame" > ## Note that "foo" attribute is lost; however... > df <- data.frame(a=1:3, b=letters[1:3]) > attr(df,"foo") <- 10 > df[["c"]] <- 10:12 > attributes(df) $names [1] "a" "b" "c" $row.names [1] 1 2 3 $foo [1] 10 $class [1] "data.frame" ## The foo attribute has been kept this time. ## Details: > sessionInfo() R version 2.6.2 (2008-02-08) i386-pc-mingw32 locale: LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MONETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252 attached base packages: [1] graphics grDevices datasets grid tcltk stats utils methods base other attached packages: [1] svSocket_0.9-5 svIO_0.9-5 svIDE_0.9-5 R2HTML_1.58 svMisc_0.9-5 lme4_0.99875-9 [7] Matrix_0.999375-4 lattice_0.17-6 > Cheers, Bert Gunter Genentech Nonclinical Statistics ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
