Message-ID: <CB3C00AC-F843-4B4B-B819-4F869E132DD4@comcast.net>
Date: 2010-01-27T02:02:15Z
From: David Winsemius
Subject: (no subject)
In-Reply-To: <20100125134640.IE314.164389.root@mp13>
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
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.