A minor issue with data.frame is a change introduced leading to R
2.5.0, where row.names=NULL (i.e., do not name rows) is not honored
with a named vector
> x <- letters[1:3]
> names(x) <- x
> data.frame(x, row.names=NULL)
x
a a
b b
c c
and a slightly more subtle example
> data.frame(y=1:3, x, row.names=NULL)
y x
a 1 a
b 2 b
c 3 c
A 2.5.0 news entry says
o data.frame() ignored 'row.names' for 0-column data frames, and
no longer treats an explicit row.names=NULL differently from
the default value.
The relevant section of ?data.frame however says
If 'row.names' was supplied as 'NULL' or no suitable
component
was found the row names are the integer sequence starting at one
This is not consistent with the current behavior, and is unchanged
from the pre 2.5.0 version. The workaround is distinctly hackish
> df <- data.frame(x)
> row.names(df) <- NULL
> sessionInfo()
R version 2.7.0 Under development (unstable) (2007-10-13 r43163)
x86_64-unknown-linux-gnu
Martin