[R] changing names of vectors in list or data.frame

[Prof Brian Ripley]

1) use names() on the resulting data frame: stack() always uses those two 
names.  As in

names(walk) <- c("walking", "training")

2) data.frame is more useful when the arguments are named, and you can 
just name them: see the help.

On Sun, 19 Feb 2006, Clint Harshaw wrote:

> When I combine separate vectors into one list, there are new names
> created. I'd like to change them to something more meaningful.
>
> Here are two examples using data(zelazo) from library(ISwR):
>
> > library(ISwR)
> > data(zelazo)
> > attach(zelazo)
> > zelazo
> $active
> [1]  9.00  9.50  9.75 10.00 13.00  9.50
>
> $passive
> [1] 11.00 10.00 10.00 11.75 10.50 15.00
>
> $none
> [1] 11.50 12.00  9.00 11.50 13.25 13.00
>
> $ctr.8w
> [1] 13.25 11.50 12.00 13.50 11.50
> > walk <- stack(list("active"=active, "passive"=passive, "none"=none,
> "ctr.8w"=ctr.8w))
> > walk
>    values     ind
> 1    9.00  active
> [...rows deleted...]
> 23  11.50  ctr.8w
>
> I want to name the first column "walking" and the second column
> "training". How do I do this?
>
> Here is a second example:
>
> > walk2 <- data.frame(c(active, passive, none, ctr.8w), c(rep(1:4,
> c(length(active), length(passive), length(none), length(ctr.8w)))))
> > walk2
>    c.active..passive..none..ctr.8w.
> 1                              9.00
> [...rows deleted...]
> 23                            11.50
>
> c.rep.1.4..c.length.active...length.passive...length.none...length.ctr.8w....
> 1
>        [...rows deleted...]
> 4
> >
>
> The created names are very long. Again, I want the name of the first
> column to be "walking" and the second column to be "training".
>
> Thanks,
> Clint
>
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-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595