Re: [R] faster vector subtraction??

About this list Date view Thread view Subject view Author view Attachment view

From: Prof Brian Ripley (ripley@stats.ox.ac.uk)
Date: Thu 17 Jan 2002 - 07:46:39 EST 

Message-id: <Pine.LNX.4.31.0201162042470.1251-100000@gannet.stats>

On Wed, 16 Jan 2002, [iso-8859-1] Søren Merser wrote:

> hi
> is there a faster way to do this?
>
> i <- 1
> for(x in vector1)
> for(y in vector2) {
> m[[i]] <- (x - y)
> i <- i + 1
> }

outer and as.list (but why do you want a list)?

outer(vector1, vector2, "-") is a good start, and
as.list(-outer(vector2, vector1, "-"))
seems to reproduce your loops. 

-- 
Brian D. Ripley,                  ripley@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@stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._

About this list Date view Thread view Subject view Author view Attachment view

This archive was generated by hypermail 2.1.3 : Thu 17 Jan 2002 - 11:10:11 EST