How to test if something doesn't exist

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