[R] The condition has length > 1 and only the first element willbeused

[Gerrit Eichner]

Hello, Pablo,

if() doesn't accept a vector as its argument the way you may want it to; 
take a look at ifelse().

  Regards  --  Gerrit


On Tue, 3 Aug 2010, Pablo Cerdeira 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
>
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> and provide commented, minimal, self-contained, reproducible code.
>

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AOR Dr. Gerrit Eichner               Mathematical Institute, Room 212
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