R help - Jan 2010 - (no subject)

Hello -- I would like to know of a more efficient way of writing the following
piece of code. Thanks.

options(stringsAsFactors=FALSE)
orig <-
c(rep('11111111',100000),rep('22222222',200000),rep('33333333',300000),rep('44444444',400000))
orig.unique <- unique(orig)
system.time(df <- as.data.frame(sapply(orig.unique, function(x)
ifelse(orig==x, 1, 0))))

Something along these lines might do the trick:

     orig <- rep(sapply(seq(from=11111111, to=44444444, by=11111111),
as.character), times=c(1, 2, 3, 4))

I've shortened the number of repetitions, so you can test it out and see if
it's what you're looking for (just change the values in the vector
assigned
to the "times" argument). It might be helpful to know a bit more about
the
specific problem you're trying to solve though.


Kyle H. Ambert
Fellow, National Library of Medicine
Department of Medical Informatics & Clinical Epidemiology
Oregon Health & Science University

On Mon, Jan 25, 2010 at 10:46 AM, Chuck White
<chuckwhite8@charter.net>wrote:
> Hello -- I would like to know of a more efficient way of writing the
> following piece of code. Thanks.
>
> options(stringsAsFactors=FALSE)
> orig <-
>
c(rep('11111111',100000),rep('22222222',200000),rep('33333333',300000),rep('44444444',400000))
> orig.unique <- unique(orig)
> system.time(df <- as.data.frame(sapply(orig.unique, function(x)
> ifelse(orig==x, 1, 0))))
>
> ______________________________________________
> R-help@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.
>
	[[alternative HTML version deleted]]

On Jan 25, 2010, at 1:46 PM, Chuck White wrote:
> Hello -- I would like to know of a more efficient way of writing the  
> following piece of code. Thanks.
>
> options(stringsAsFactors=FALSE)
> orig <- c(rep('11111111',100000),rep('22222222', 
> 200000),rep('33333333',300000),rep('44444444',400000))
> orig.unique <- unique(orig)
> system.time(df <- as.data.frame(sapply(orig.unique, function(x)  
> ifelse(orig==x, 1, 0))))
 > system.time(df <- model.matrix(~orig))
    user  system elapsed
   3.122   0.204   3.312
Warning message:
In model.matrix.default(~orig) : variable 'orig' converted to a factor
 >
 > options(stringsAsFactors=FALSE)
 > orig <- c(rep('11111111',100000),rep('22222222', 
200000),rep('33333333',300000),rep('44444444',400000))
 > orig.unique <- unique(orig)
 > system.time(df <- as.data.frame(sapply(orig.unique, function(x)  
ifelse(orig==x, 1, 0))))
    user  system elapsed
  18.455   0.872  19.234

>
> ______________________________________________
> 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.