[R] If loops?

[David Winsemius]

On Nov 1, 2012, at 6:38 PM, arun wrote:

> Hi,
> 
> You can try this also :
> set.seed(132)
>  dat1<-data.frame(Company=rep(LETTERS[1:4],c(3,4,5,6)),Last_year=sample(2005:2012,18,replace=TRUE))
> dat2<-dat1[order(dat1$Company,dat1$Last_year),]
> dat2$Last<-ave(dat2$Last_year,dat2$Company,FUN=function(x) ifelse(x>=2009,2009,x))

 None of the `ifelse` conditional or desired consequent depend on the Company value. Just wasted CPU cycles are the result. If you choose to use `ifelse` , then why not:

dat2$Last2<- ifelse(dat2$Last_year > 2009, 2009, dat2$Last_year)      # the '=' also not needed


head(dat2)
> 
> #  Company Last_year Last
> #3       A      2007 2007
> #1       A      2010 2009
> #2       A      2012 2009
> #6       B      2007 2007
> #4       B      2008 2008
> #5       B      2008 2008
> 
> identical(dat2[,3],pmin(dat2[,2],2009))
> #[1] TRUE
> 
> identical(dat2[,4],pmin(dat2[,2],2009))
[1] TRUE

> A.K.
> 
> 
> 
> ----- Original Message -----
> From: kebrab67 <selamgetachew at gmail.com>
> To: r-help at r-project.org
> Cc: 
> Sent: Thursday, November 1, 2012 8:41 PM
> Subject: [R] If loops?
> 
> I have a set of data with  205 988 observation sand 10 variables , three of
> which are Legal_status, Date_of_incorporation and Last_year. I set my time
> horizon from 1989 to 2009. Now I want to know when a company is dead. If
> Last_year is bigger or equal to 2009 then I say that a new "variable" last
> is 2009. If Last_year is smaller than 2009 then my new variable "last" is
> equal to the variable "Last_year". I wanted to know how I can generate this
> new variable and connect it to my original data called data.
> 
> 
> 
> --
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> 

David Winsemius, MD
Alameda, CA, USA