R help - May 2013 - How to test if something doesn't exist

Couldn't exactly explain the subject, so here's  the example:

idx<-which(blah[,1]=="xyz")
idx
integer(0)

How do I test that idx has a valid value (namely, > 0)?

TiA,
Joe

Hi Joe,
Not sure about your expected result
?blah<- paste0("x",1:5)
?which(blah=="xyz")
#integer(0)
blah=="xyz"
#[1] FALSE FALSE FALSE FALSE FALSE
?any(blah=="xyz")
#[1] FALSE


?sum(blah=="xyz")
#[1] 0
sum(blah=="x1")
#[1] 1
A.K.



----- Original Message -----
From: Joseph Trubisz <jtrubisz at me.com>
To: r-help at r-project.org
Cc: 
Sent: Wednesday, May 22, 2013 2:08 PM
Subject: [R] How to test if something doesn't exist

Couldn't exactly explain the subject, so here's? the example:

idx<-which(blah[,1]=="xyz")
idx
integer(0)

How do I test that idx has a valid value (namely, > 0)?

TiA,
Joe

______________________________________________
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.

#Some cases: 

ifelse(blah!="xyz",paste0(blah,1),blah)
#[1] "x11" "x21" "x31" "x41"
"x51"

if(sum(blah=="xyz")>0) blah else paste0(blah,1)
#[1] "x11" "x21" "x31" "x41"
"x51"

if(any(blah=="xyz")) blah else as.numeric(factor(blah))
#[1] 1 2 3 4 5
A.K.






----- Original Message -----
From: Joseph Trubisz <jtrubisz at me.com>
To: arun <smartpink111 at yahoo.com>
Cc: 
Sent: Wednesday, May 22, 2013 2:37 PM
Subject: Re: [R] How to test if something doesn't exist

OK...got it...thanks....

Joe


On May 22, 2013, at 2:34 PM, arun <smartpink111 at yahoo.com> wrote:
> 
> any(blah=="xyz") #gives FALSE as mentioned in the preivous email.
> 
> 
> 
> 
> ----- Original Message -----
> From: Joseph Trubisz <jtrubisz at me.com>
> To: arun <smartpink111 at yahoo.com>
> Cc: 
> Sent: Wednesday, May 22, 2013 2:32 PM
> Subject: Re: [R] How to test if something doesn't exist
> 
> Problem is how do you test it?
> In the example, I KNOW it doesn't exist, and I don't want to do a
block of code that follows if it does not.
> 
> Example:
> 
> idx<-which(blah[,1]=="xxx")
> if( idx>0) #doesn't work...what does?
> {
> ...
> }
> 
> 
> On May 22, 2013, at 2:29 PM, arun <smartpink111 at yahoo.com> wrote:
> 
>> Hi Joe,
>> Not sure about your expected result
>>?  blah<- paste0("x",1:5)
>>?  which(blah=="xyz")
>> #integer(0)
>> blah=="xyz"
>> #[1] FALSE FALSE FALSE FALSE FALSE
>>?  any(blah=="xyz")
>> #[1] FALSE
>> 
>> 
>>?  sum(blah=="xyz")
>> #[1] 0
>> sum(blah=="x1")
>> #[1] 1
>> A.K.
>> 
>> 
>> 
>> ----- Original Message -----
>> From: Joseph Trubisz <jtrubisz at me.com>
>> To: r-help at r-project.org
>> Cc: 
>> Sent: Wednesday, May 22, 2013 2:08 PM
>> Subject: [R] How to test if something doesn't exist
>> 
>> Couldn't exactly explain the subject, so here's? the example:
>> 
>> idx<-which(blah[,1]=="xyz")
>> idx
>> integer(0)
>> 
>> How do I test that idx has a valid value (namely, > 0)?
>> 
>> TiA,
>> Joe
>> 
>> ______________________________________________
>> 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.
>> 
>

Joe

Testing is something _exists_ is different than testing if something has what
you are referring to as a valid value. Here is one way to do what I think you
are doing versus testing if something exists

validVal <- function(x, val){
	if (!is.numeric(x)) stop('Not a numeric variable')
	else x > val
	}

x <- 1
y <- 'foo'

validVal(x, 0)
validVal(x, 1)
validVal(y, 0)

exists('x')


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Joseph Trubisz
Sent: Wednesday, May 22, 2013 2:09 PM
To: r-help at r-project.org
Subject: [R] How to test if something doesn't exist

Couldn't exactly explain the subject, so here's  the example:

idx<-which(blah[,1]=="xyz")
idx
integer(0)

How do I test that idx has a valid value (namely, > 0)?

TiA,
Joe

______________________________________________
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.