R devel - Aug 2007 - hasNA() / anyNA()?

Hi,

is there a hasNA() / an anyNA() function in R?  Of course,

hasNA <- function(x) {
  any(is.na(x));
}

would do, but that would scan all elements in 'x' and then do the
test.  I'm looking for a more efficient implementation that returns
TRUE at the first NA, e.g.

hasNA <- function(x) {
  for (kk in seq(along=x)) {
    if (is.na(x[kk]))
      return(TRUE);
  }
  FALSE;
}

Cheers

Henrik

I don't know of one.

Ideally, instead of a specifc function anyNA()  function, any() could be
perhaps be extended to any(x, FUN) where FUN returns a logical for an
element of x, and implemented to find the 1st instance as you suggest.

Mike

On 8/13/07, Henrik Bengtsson <hb@stat.berkeley.edu>
wrote:
>
> Hi,
>
> is there a hasNA() / an anyNA() function in R?  Of course,
>
> hasNA <- function(x) {
>   any(is.na(x));
> }
>
> would do, but that would scan all elements in 'x' and then do the
> test.  I'm looking for a more efficient implementation that returns
> TRUE at the first NA, e.g.
>
> hasNA <- function(x) {
>   for (kk in seq(along=x)) {
>     if (is.na(x[kk]))
>       return(TRUE);
>   }
>   FALSE;
> }
>
> Cheers
>
> Henrik
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
	[[alternative HTML version deleted]]

Why not

hasNA <- function(x) !is.na(match(NA, x))

-Ben

S-PLUS has an anyMissing() function, for which the default is:

anyMissing.default <-
function(x){
	(length(which.na(x)) > 0)
}

This is more efficient than any(is.na(x)) in the usual case that there
are few or no missing values.  There are methods for vectors that drop
to C code, and methods for data frames and other classes.

The code below seems to presume a list, and would be very slow for vectors.

For reasons of consistency between S-PLUS and R, I would ask that an R
function be called anyMissing rather than hasNA or anyNA.

Tim Hesterberg
>is there a hasNA() / an anyNA() function in R?  Of course,
>
>hasNA <- function(x) {
>  any(is.na(x));
>}
>
>would do, but that would scan all elements in 'x' and then do the
>test.  I'm looking for a more efficient implementation that returns
>TRUE at the first NA, e.g.
>
>hasNA <- function(x) {
>  for (kk in seq(along=x)) {
>    if (is.na(x[kk]))
>      return(TRUE);
>  }
>  FALSE;
>}
>
>Cheers
>
>Henrik