[R] The condition has length > 1 and only the first element will be used

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 03.08.2010 13:17:16:

> Ok thanks, but I have found the solution: "ifelse".
> 
> Here goes a working version of the code:
> 
> mod = function(x) {
>   ifelse(x < 0,x*(-1),x)
> }

But before you reinvent wheel try to look if there is not available 
function already

> system.time(y1<-mod(x))
   user  system elapsed 
   4.09    0.56    4.68 
> system.time(y2<-abs(x))
   user  system elapsed 
   0.10    0.02    0.11 
> all.equal(y1,y2)
[1] TRUE
>

Regards
Petr

> f = function(x) {
>   f <- mod(x)/x
> }
> x <- seq(-1,1,0.01)
> x
> y <- f(x)
> y
> plot(f,xlim = c(-1,1))
> remove(x,y,f,mod)
> 
> best regards
> 
> 
> On Tue, Aug 3, 2010 at 8:03 AM, Pablo Cerdeira 
<pablo.cerdeira at gmail.com> wrote:
> > Hi All,
> >
> > I'm trying to run the following script in R, but I'm getting a warning 
saying:
> >
> > Warning message:
> > In if (z < 0) { :
> >  the condition has length > 1 and only the first element will be used
> >
> > As you can see, I'm sending a vector x to the function f without any
> > problem. The function f calculates the y value for each x.
> >
> > But the function f needs to convert the x to positive values (the mod
> > function). And when it tries to convert, it always uses the first
> > value of x.
> >
> > What I'm doing wrong here?
> >
> > mod = function(x) {
> >  if (x < 0) {
> >    mod <- x*(-1)
> >  }
> >  else {
> >    mod <- x
> >  }
> > }
> > f = function(x) {
> >  f <- mod(x)/x
> > }
> > x <- seq(-1,1,0.01)
> > x
> > y <- f(x)
> > y
> > plot(f,xlim = c(-1,1))
> > remove(x,y,f,mod)
> >
> > best regards,
> >
> > --
> > Pablo de Camargo Cerdeira
> > pablo at fgv.br
> > pablo.cerdeira at gmail.com
> > +55 (21) 3799-6065
> >
> 
> 
> 
> -- 
> Pablo de Camargo Cerdeira
> pablo at fgv.br
> pablo.cerdeira at gmail.com
> +55 (21) 3799-6065
> 
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