[R] How to get rid of loop?

[Peter Alspach]

Tena koe Ken

Would something along the following lines do what you require:

set.seed(1)
x <- runif(100)
y <- rep(NA, length(x))
y[x<0.25] <- -1
y[x>0.75] <- 1
y[-1][y[-length(y)]%in%1 & (x[-1]>=0.25 & x[-1]<0.5)] <- 0
# etc

HTH ....

Peter Alspach

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Ken-JP
> Sent: Saturday, 25 April 2009 12:16 p.m.
> To: r-help at r-project.org
> Subject: [R] How to get rid of loop?
> 
> 
> set.seed(1)
> x <- runif(100)
> 
> # I want to calculate y such that:
> #
> # 1. if x>0.75, y <- 1
> # 2. else if x<0.25, y <- -1
> # 3. else if y_prev==1 && x<0.5, y <- 0
> # 4. else if y_prev==-1 && x>0.5, y <- 0 # 5. else y <- 
> y_prev # # 1. and 2. are directly doable without looping.
> #
> # How do I do 3.-5. without looping?  The problem is, I need 
> to run this algorithm over gigs of data, so I # need to avoid 
> looping, if at all possible...
> #
> # - Ken
> 
> 
> 
> --
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> 
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