Message-ID: <10dee4690504152007da45866@mail.gmail.com>
Date: 2005-04-16T03:07:01Z
From: Fernando Saldanha
Subject: Getting subsets of a data frame
I was reading in the Reference Manual about Extract.data.frame.
There is a list of examples of expressions using [ and [[, with the
outcomes. I was puzzled by the fact that, if sw is a data frame, then
sw[, 1:3]
is also a data frame,
but
sw[, 1]
is just a vector.
Since R has no scalars, it must be the case that 1 and 1:1 are the same:
> 1 == 1:1
[1] TRUE
Then why isn't sw[,1] = sw[, 1:1] a data frame?
FS