R help - May 2005 - comparing a vactor of values in IF statement.

Hi,
  
 my vector V<- c(1,0.5,0.06,0.056,0.01,0.04,0.4,0.9,0.82,0.1)
 
  if( V > 0.5) { V <- 1 - V }
 
I get  a warning saying only the first element will be used in comparing (if V
> 0.5).
However, my results tell me vis-versa ,it actually compares every element of the
vector V with 0.5 and that is waht i want it to do.
Using a for loop is expensive and time consuming since my actual vector is 15000
values.
 
Any help to rectify the warning i get is appreciated. 
 
Thank You. 
 
Choudary Jagarlamudi
Instructor
Southwestern Oklahoma State University
STF 254
100 campus Drive
Weatherford OK 73096
Tel 580-774-7136

	[[alternative HTML version deleted]]

Try

  V <- ifelse(V > 0.5, 1-V, V)

or 

  V <- pmin(V, 1-V)


On 5/20/05, Jagarlamudi, Choudary <choudary.jagar at swosu.edu>
wrote:
> Hi,
> 
>  my vector V<- c(1,0.5,0.06,0.056,0.01,0.04,0.4,0.9,0.82,0.1)
> 
>  if( V > 0.5) { V <- 1 - V }
> 
> I get  a warning saying only the first element will be used in comparing
(if V > 0.5).
> However, my results tell me vis-versa ,it actually compares every element
of the vector V with 0.5 and that is waht i want it to do.
> Using a for loop is expensive and time consuming since my actual vector is
15000 values.
> 
> Any help to rectify the warning i get is appreciated.
> 
> Thank You.
> 
> Choudary Jagarlamudi
> Instructor
> Southwestern Oklahoma State University
> STF 254
> 100 campus Drive
> Weatherford OK 73096
> Tel 580-774-7136
> 
>        [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>

Both

V[V > 0.5] <- 1 - V[V > 0.5]

and 

ifelse(V>0.5, 1-V,V)

should do it.

Ravi.

--------------------------------------------------------------------------
Ravi Varadhan, Ph.D.
Assistant Professor,  The Center on Aging and Health
Division of Geriatric Medicine and Gerontology
Johns Hopkins University
Ph: (410) 502-2619
Fax: (410) 614-9625
Email:  rvaradhan at jhmi.edu
--------------------------------------------------------------------------
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-
> bounces at stat.math.ethz.ch] On Behalf Of Jagarlamudi, Choudary
> Sent: Friday, May 20, 2005 1:59 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] comparing a vactor of values in IF statement.
> 
> Hi,
> 
>  my vector V<- c(1,0.5,0.06,0.056,0.01,0.04,0.4,0.9,0.82,0.1)
> 
>   if( V > 0.5) { V <- 1 - V }
> 
> I get  a warning saying only the first element will be used in comparing
> (if V > 0.5).
> However, my results tell me vis-versa ,it actually compares every element
> of the vector V with 0.5 and that is waht i want it to do.
> Using a for loop is expensive and time consuming since my actual vector is
> 15000 values.
> 
> Any help to rectify the warning i get is appreciated.
> 
> Thank You.
> 
> Choudary Jagarlamudi
> Instructor
> Southwestern Oklahoma State University
> STF 254
> 100 campus Drive
> Weatherford OK 73096
> Tel 580-774-7136
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-
> guide.html