[R] or of a logical vector

[Baskin, Robert]

I don't know how careful about coercing type you need to be.

Something like TRUE %in% outer(v,v,"|") may work for you but simpler
functions that do arithmetic and coerce the answer back to logical [e.g.,
as.logical(max(v))] might suffice.

> xt <- c(T,T,T)
> xf <- c(T,F,F)
> outer(xt, xf, "|")
     [,1] [,2] [,3]
[1,] TRUE TRUE TRUE
[2,] TRUE TRUE TRUE
[3,] TRUE TRUE TRUE
> outer(xf, xf, "|")
     [,1]  [,2]  [,3]
[1,] TRUE  TRUE  TRUE
[2,] TRUE FALSE FALSE
[3,] TRUE FALSE FALSE
> TRUE %in% outer(xf, xf, "|")
[1] TRUE
> TRUE %in% outer(!xt, !xt, "|")
[1] FALSE
> #if you don't mind sloppiness
> as.logical(max(xf))
[1] TRUE
> as.logical(max(!xt))
[1] FALSE
> as.logical(sum(xf^2))
[1] TRUE
> as.logical(sum((!xt)^2))
[1] FALSE
> #be careful
> as.logical(max(c(-1,0,0))
+ )
[1] FALSE
> 

bob




-----Original Message-----
From: Ben Wittner [mailto:bwittner at jimmy.harvard.edu] 
Sent: Thursday, August 05, 2004 12:38 PM
To: r-help at stat.math.ethz.ch
Subject: [R] or of a logical vector


Is there some fast (built-in?) way to get the OR of all the elements in a
logical vector?

In other words, is there some fast (built-in) version of the function vor
below?

Thanks.

-Ben

vor <- function(v) {
  ans <- v[1]
  if (length(v) > 1)
    for (i in 2:length(v))
      ans <- ans | v[i]
  ans
}

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