[R] subset of matrix vs data frame

[Prof Brian D Ripley]

On Wed, 31 May 2000, Denis White wrote:

> In Splus this works,
> 
> > a <- data.frame(matrix(round(runif(10),0),nrow=2,ncol=5))
> > a[a == 1] <- 2
> 
> but in R only if a is matrix,
> 
> > a[a == 1] <- 2
> Error in [<-.data.frame(*tmp*, a == 1, value = 2) : 
>         matrix subscripts not allowed in replacement
> 
> Was this a design decision?  Sorry if I missed it in
> An Introduction to R.

S-PLUS differs from the original S here, as I understand it.
So it was an S-PLUS design decision as I understand it. S-PLUS says:

        else if(nargs() == 3) {
# really ambiguous, but follow common use as if list, 
# except when one subscript is a logical matrix the shape of x, then treat
# as if x were a matrix.


-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._