From: Liaw, Andy <andy_liaw_at_merck.com>

Date: Fri 13 Jan 2006 - 06:41:29 EST

[53] -1 -1 -1 -1 -1 1 1 -1 1 -1 -1 -1 1 -1 -1 1 -1 1 -1 1 -1 -1 -1 1 1 -1

[79] 1 1 -1 1 -1 -1 1 -1 1 -1 -1 -1 -1 -1 1 1 1 1 -1 -1 1 1

*> r <- rle(x)$length
*

*> p <- which(r == 3)
*

> idx <- cumsum(r)[p] - 2

> sapply(idx, function(i) x[i:(i+2)])

*> idx
*

[1] 10 35 62 73

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jan 13 06:48:18 2006

Date: Fri 13 Jan 2006 - 06:41:29 EST

Mark,

It's a bit unclear whether you're looking for a run of exactly 3, or at least 3. If it's exactly 3, what Prof. Koenker suggested (using rle()) should help you a lot. If you want runs of at least 3, it should work similarly as well.

> set.seed(1)

> (x <- sample(c(-1, 1), 100, replace=TRUE))

[1] -1 -1 1 1 -1 1 1 1 1 -1 -1 -1 1 -1 1 -1 1 1 -1 1 1 -1 1 -1 -1 -1 [27] -1 -1 1 -1 -1 1 -1 -1 1 1 1 -1 1 -1 1 1 1 1 1 1 -1 -1 11 -1 1

[53] -1 -1 -1 -1 -1 1 1 -1 1 -1 -1 -1 1 -1 -1 1 -1 1 -1 1 -1 -1 -1 1 1 -1

[79] 1 1 -1 1 -1 -1 1 -1 1 -1 -1 -1 -1 -1 1 1 1 1 -1 -1 1 1

> idx <- cumsum(r)[p] - 2

> sapply(idx, function(i) x[i:(i+2)])

[,1] [,2] [,3] [,4]

[1,] -1 1 -1 -1 [2,] -1 1 -1 -1 [3,] -1 1 -1 -1

[1] 10 35 62 73

Andy

From: Mark Leeds

*>
*

> I'm sorry to bother this list so much

*> But I haven't programmed in
**> A while and I'm struggling.
**>
**> I have a vector in R of 1's and -1's
**> And I want to use a streak of size Y
**> To predict that the same value will
**> Be next.
**>
**> So, suppose Y = 3. Then, if there is a streak of three
**> ones in a row, then I will predict that the next value is
**> a 1. But, if there is a streak of 3 -1's in a row,
**> then I will predict that a -1 is next. Otherwise,
**> I don't predict anything.
**>
**> I am really new to R and kind of struggling
**> And I was wondering if someone could show
**> how to do this ?
**>
**> In other words, given a vector of -1's
**> And 1's, I am unable ( I've been trying
**> For 2 days ) to create a new vector that
**> Has the predictions in it at the appropriate
**> places ? Thanks.
**>
**>
**>
**>
**> **********************************************************************
**> This email and any files transmitted with it are
**> confidentia...{{dropped}}
**>
**> ______________________________________________
**> R-help@stat.math.ethz.ch mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide!
**> http://www.R-project.org/posting-guide.html
**>
*

>

R-help@stat.math.ethz.ch mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Jan 13 06:48:18 2006

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