>>>>> "RF" == Romain Francois <romain.franc...@dbmail.com>
>>>>> on Sun, 11 Oct 2009 01:00:24 +0200 writes:
RF> Hello, Just wondering why there is "isTRUE" and not
RF> "isFALSE".
Probably because it's slightly more natural to have
if(isTRUE(....)) {
..
}
rather than the corrsponding isFALSE()
Further, e.g. all.equal() and validObject()
return *either* TRUE or a string,
and hence isTRUE(.) is usefully applied to their return values.
Are there other opinions on this?
Martin
> --
> Romain Francois
> Professional R Enthusiast
> +33(0) 6 28 91 30 30
> http://romainfrancois.blog.free.fr
> |- http://tr.im/BcPw : celebrating R commit #50000
> |- http://tr.im/ztCu : RGG #158:161: examples of package IDPmisc
> `- http://tr.im/yw8E : New R package : sos
> Index: src/library/base/R/identical.R
> ===================================================================
> --- src/library/base/R/identical.R (revision 50027)
> +++ src/library/base/R/identical.R (working copy)
> @@ -18,3 +18,5 @@
> .Internal(identical(x,y, num.eq, single.NA, attrib.as.set))
> isTRUE <- function(x) identical(TRUE, x)
> +
> +isFALSE <- function(x) identical(FALSE, x)
> Index: src/library/base/man/Logic.Rd
> ===================================================================
> --- src/library/base/man/Logic.Rd (revision 50027)
> +++ src/library/base/man/Logic.Rd (working copy)
> @@ -14,6 +14,7 @@
> xor(x, y)
> isTRUE(x)
> +isFALSE(x)
> }
> \alias{!}
> \alias{&}
> @@ -23,6 +24,7 @@
> \alias{xor}
> \alias{Logic}
> \alias{isTRUE}
> +\alias{isFALSE}
> \description{
> These operators act on logical and number-like vectors.
> }
> @@ -48,7 +50,11 @@
> \code{isTRUE(x)} is an abbreviation of \code{identical(TRUE, x)}, and
> so is true if and only if \code{x} is a length-one logical vector with
> no attributes (not even names).
> -
> +
> + \code{isFALSE(x)} is an abbreviation of \code{identical(FALSE, x)}, and
> + so is true if and only if \code{x} is a length-one logical vector with
> + no attributes (not even names).
> +
> Numeric and complex vectors will be coerced to logical values, with
> zero being false and all non-zero values being true. Raw vectors are
> handled without any coercion for \code{!}, \code{&}, \code{|} and
> @@ -87,7 +93,7 @@
> used. For arrays (and an array result) the dimensions and dimnames
> are taken from first argument if it is an array, otherwise the second.
> - For \code{||}, \code{&&} and \code{isTRUE}, a length-one logical
vector.
> + For \code{||}, \code{&&}, \code{isFALSE} and \code{isTRUE}, a
length-one logical vector.
> }
> \section{S4 methods}{
> \code{!}, \code{&} and \code{|} are S4 generics, the latter two part
> Index: src/library/base/man/identical.Rd
> ===================================================================
> --- src/library/base/man/identical.Rd (revision 50027)
> +++ src/library/base/man/identical.Rd (working copy)
> @@ -85,7 +85,8 @@
> \seealso{
> \code{\link{all.equal}} for descriptions of how two objects differ;
> \link{Comparison} for operators that generate elementwise comparisons.
> - \code{\link{isTRUE}} is a simple wrapper based on \code{identical}.
> + \code{\link{isTRUE}} and \code{\link{isFALSE}} are simple
> + wrappers based on \code{identical}.
> }
> \examples{
> identical(1, NULL) ## FALSE -- don't try this with ==
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