[R] If else in R code

[Simon Blomberg]

How about:

a<-c("2001-02-1",NA,NA)
b<-c("2001-03-1","2001-03-2","2001-03-3")

 res <- ifelse(is.na(a), as.character(as.Date(b)-2),
as.character(as.Date(a)))
res

Or with no ifelse:

 res <- a
 res[is.na(a)] <- as.character(as.Date(b[is.na(a)])-2)
 res

Cheers,

Simon.

On Fri, 2008-02-08 at 14:23 +1300, Andrew McFadden wrote:
> Hi There 
> 
> I am a new user of "R" and having a few problems
> 
> a<-c("2001-02-1","NA","NA")
> a<-as.Date(a,format = "%Y-%m-%d")
> 
> b<-c("2001-03-1","2001-03-2","2001-03-3")
> b<-as.Date(b,format = "%Y-%m-%d")
> 
> c<-data.frame(a,b)
> 
> I would like to write an if statement where if "a" is not null return
> "a", if "a" is null (NA) return "b" less two days. Could someone help?.
> 
> 
> Andrew  
> 
> 
> 
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-- 
Simon Blomberg, BSc (Hons), PhD, MAppStat. 
Lecturer and Consultant Statistician 
Faculty of Biological and Chemical Sciences 
The University of Queensland 
St. Lucia Queensland 4072 
Australia
Room 320 Goddard Building (8)
T: +61 7 3365 2506
http://www.uq.edu.au/~uqsblomb
email: S.Blomberg1_at_uq.edu.au

Policies:
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2.  Your deadline is your problem.

The combination of some data and an aching desire for 
an answer does not ensure that a reasonable answer can 
be extracted from a given body of data. - John Tukey.