R help - Oct 2014 - apply if else statement to vector

Subscribers,

What is the correct syntax to apply the 'if else' conditional statement 
to vector objects?

Example:

vectorx<-c(50,50,20,70)
vectory<-c(50,50,20,20)
vectorz<-function () {
	if (vectorx>vectory)
	vectorx
	else vectorx<-0
}

vectorz()
Warning message:
In if (vectorx > vectory) vectorx else vectorx <- 0 :
   the condition has length > 1 and only the first element will be used

The help manual (?'if') explains that only length=0 is acceptable; what 
is an appropriate alternative function to use please?

The desired result for vectorz is:

0 0 0 70

Hi

in this case correct syntax is not to use if at all

vectorx*(vectorx>vectory)
1]  0  0  0 70

if you insist you can use

?ifelse

which is "vectorised" if

Regards
Petr

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of rl at openmailbox.org
> Sent: Thursday, October 02, 2014 11:02 AM
> To: r-help at r-project.org
> Subject: [R] apply if else statement to vector
>
> Subscribers,
>
> What is the correct syntax to apply the 'if else' conditional
statement
> to vector objects?
>
> Example:
>
> vectorx<-c(50,50,20,70)
> vectory<-c(50,50,20,20)
> vectorz<-function () {
>       if (vectorx>vectory)
>       vectorx
>       else vectorx<-0
> }
>
> vectorz()
> Warning message:
> In if (vectorx > vectory) vectorx else vectorx <- 0 :
>    the condition has length > 1 and only the first element will be used
>
> The help manual (?'if') explains that only length=0 is acceptable;
what
> is an appropriate alternative function to use please?
>
> The desired result for vectorz is:
>
> 0 0 0 70
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
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On 02-10-2014, at 11:01, rl at openmailbox.org wrote:
> Subscribers,
> 
> What is the correct syntax to apply the 'if else' conditional
statement to vector objects?
> 
> Example:
> 
> vectorx<-c(50,50,20,70)
> vectory<-c(50,50,20,20)
> vectorz<-function () {
> 	if (vectorx>vectory)
> 	vectorx
> 	else vectorx<-0
> }
> 
> vectorz()
> Warning message:
> In if (vectorx > vectory) vectorx else vectorx <- 0 :
>  the condition has length > 1 and only the first element will be used
> 
> The help manual (?'if') explains that only length=0 is acceptable;
what is an appropriate alternative function to use please?
> 
And at the bottom of that page (section See Also) there is a reference to
ifelse. Why didn?t you have a look at that?

Replace your complete if/else statement with
ifelse(vectorx>vectory,vectorx,0)

Berend

> 
> 0 0 0 70
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.