R help - Feb 2009 - problem with using %in% condition while using in if() condition

Hi all,
I got one problem with using %in% condition while using in if() condition
where
I used the condition as


if(SubFinSpt$SPECIMENTYP %in% CAP$SPECIMENTYP)

this   "if()"    condition is in      "else"     condition
and hear  "*SubFinSpt$SPECIMENTYP*" having only one value   but
"*CAP$SPECIMENTYP"
*having nearly 20 SPECIMENTYP's

while applying this condition I got one warning that says  only first
element is checked
and after that warning it is executing normally and giving results
but i want to know why it is giving this warning

can any one explain why it is comming and how to resolve it

thanks in advance

	[[alternative HTML version deleted]]

Hi

r-help-bounces at r-project.org napsal dne 19.02.2009 07:15:00:
> Hi all,
> I got one problem with using %in% condition while using in if() 
condition
> where
> I used the condition as
> 
> 
> if(SubFinSpt$SPECIMENTYP %in% CAP$SPECIMENTYP)
SubFinSpt$SPECIMENTYP %in% CAP$SPECIMENTYP

gives you logical vector

"if" works only with the first value of this vector

see

?"if"
?"ifelse"

Regards
Petr

> 
> this   "if()"    condition is in      "else"    
condition
> and hear  "*SubFinSpt$SPECIMENTYP*" having only one value   but
> "*CAP$SPECIMENTYP"
> *having nearly 20 SPECIMENTYP's
> 
> while applying this condition I got one warning that says  only first
> element is checked
> and after that warning it is executing normally and giving results
> but i want to know why it is giving this warning
> 
> can any one explain why it is comming and how to resolve it
> 
> thanks in advance
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.

The %in% operator returns a vector of logicals the same length as the vector to
the left. The if program flow operator expects a single logical value, not a
vector, since you are giving it a vector it looks at just the 1st element,
ignores the rest and gives the warning.  This warning should be taken seriously
since it indicates that what is happening and what you intend probably do not
match.

If you tell us more about what you are trying to do, we can give more help.

Some possibilities:  use any() or all() to reduce the vector to a single logical
value.
Use ifelse(), subscripting, or some other method to accomplish what you want.


-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of venkata kirankumar
> Sent: Wednesday, February 18, 2009 11:15 PM
> To: r-help at r-project.org
> Subject: [R] problem with using %in% condition while using in if()
> condition
> 
> Hi all,
> I got one problem with using %in% condition while using in if()
> condition
> where
> I used the condition as
> 
> 
> if(SubFinSpt$SPECIMENTYP %in% CAP$SPECIMENTYP)
> 
> this   "if()"    condition is in      "else"    
condition
> and hear  "*SubFinSpt$SPECIMENTYP*" having only one value   but
> "*CAP$SPECIMENTYP"
> *having nearly 20 SPECIMENTYP's
> 
> while applying this condition I got one warning that says  only first
> element is checked
> and after that warning it is executing normally and giving results
> but i want to know why it is giving this warning
> 
> can any one explain why it is comming and how to resolve it
> 
> thanks in advance
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.