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Ben Wittner

2004-Aug-05 16:38 UTC

[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
}

Eric Lecoutre

2004-Aug-05 18:19 UTC

head link

[R] or of a logical vector

Hi Ben,

Always do consider that boolean vectors TRUE/FALSE are equivalent to 
integers 1/0.
What you want is to know wether one element of a vector is TRUE, which is:

 > sum(vec)>0

HTH,

Eric



At 18:38 5/08/2004, Ben Wittner wrote:>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
>}
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
Eric Lecoutre
UCL /  Institut de Statistique
Voie du Roman Pays, 20
1348 Louvain-la-Neuve
Belgium

tel: (+32)(0)10473050
lecoutre at stat.ucl.ac.be
http://www.stat.ucl.ac.be/ISpersonnel/lecoutre

If the statistics are boring, then you've got the wrong numbers. -Edward 
Tufte

Spencer Graves

2004-Aug-05 18:19 UTC

head link

[R] or of a logical vector

?any

hope this helps.  spencer graves

Ben Wittner wrote:
>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
>}
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
>https://www.stat.math.ethz.ch/mailman/listinfo/r-help
>PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>  
>

Gabor Grothendieck

2004-Aug-05 18:19 UTC

head link

[R] or of a logical vector

Ben Wittner <bwittner <at> jimmy.harvard.edu> writes:

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

Here are two possibilities:

max(x) == 1
sum(x) > 0

These use the fact that logicals used in arithmetic operations
are converted such that TRUE becomes 1 and FALSE becomes 0.

Liaw, Andy

2004-Aug-05 18:41 UTC

head link

[R] or of a logical vector

Is there anything wrong with sum(v) > 0?

Andy
> From: Ben Wittner
> 
> 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
> }
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> 
>

Jeff Gentry

2004-Aug-05 19:05 UTC

head link

[R] Re: or of a logical vector

> Is there some fast (built-in?) way to get the OR of all the elements in
> a logical vector?
any() and all() should give you OR and AND, respectively.  Perhaps this
should be in as a 'see also' for '|' and '&'.

-J

Baskin, Robert

2004-Aug-05 19:15 UTC

head link

[R] or of a logical vector

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
}

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html

(Ted Harding)

2004-Aug-05 19:22 UTC

head link

[R] or of a logical vector

On 05-Aug-04 Ben Wittner wrote:> 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
> }
It's a sort of cheating ("type-punning"), but so long as it's
just
the "or" you're after then

  sum(v)>0

will implement your 'vor', i.e. give you FALSE if all v[i]==FALSE,
and TRUE if any v[i]==TRUE. And it's certainly fast.

Similarly,

  prod(v)>0

would implement a 'vand'.

But you can also do these with 'any' and 'all', e.g.

  any(v==TRUE)

and

  all(v==TRUE)

I'm not sure which of these two approaches would be faster, but
I doubt there's much in it.

Best wishes,
Ted.


--------------------------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk>
Fax-to-email: +44 (0)870 167 1972
Date: 05-Aug-04                                       Time: 20:22:12
------------------------------ XFMail ------------------------------

Liaw, Andy

2004-Aug-05 20:23 UTC

head link

[R] or of a logical vector

Yes, of course:
> x <- c(TRUE, NA)
> any(x)
[1] TRUE> sum(x) > 0[1] NA

Andy
> From: Peter Dalgaard  
> 
> "Liaw, Andy" <andy_liaw at merck.com> writes:
> 
> > Is there anything wrong with sum(v) > 0?
> 
> Yes, there is an any()-thing.... ;-)
> 
> (And NA handling differs too.)
> 
> -- 
>    O__  ---- Peter Dalgaard             Blegdamsvej 3  
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: 
> (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: 
> (+45) 35327907
> 
>

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