R help - Feb 2012 - Detect numerical series

Hello,

I am struggling with detecting successive digits in a numerical series
vector.

Here is an example:

vec <- c(1, 15, 26, 29, 30, 31, 37, 40, 41)

I want to be able to detect 29, 30, 31 and 40, 41.

Then, I would like to delete the successive digits from the vector.

1, 15, 26, 29, 37, 40


Cheers

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On Feb 11, 2012, at 10:01 AM, syrvn wrote:
> Hello,
>
> I am struggling with detecting successive digits in a numerical series
> vector.
>
> Here is an example:
>
> vec <- c(1, 15, 26, 29, 30, 31, 37, 40, 41)
>
> I want to be able to detect 29, 30, 31 and 40, 41.
>
> Then, I would like to delete the successive digits from the vector.
>
> 1, 15, 26, 29, 37, 40
  vec[ c(TRUE, !diff(vec) == 1) ]
#[1]  1 15 26 29 37 40
>
>
> Cheers
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Detect-numerical-series-tp4379088p4379088.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.
David Winsemius, MD
West Hartford, CT

This was actually answered a couple times in StackOverflow.  Someone and 
I indpendently wrote up the following function, stolen directly from the 
source for rle().


# extended version of rle to find all sorts of sequences
# if incr=0, this is rle

seqle<- function (x,incr=1)
{
     if (!is.vector(x) && !is.list(x))
         stop("'x' must be an atomic vector")
     n <- length(x)
     if (n == 0L)
         return(structure(list(lengths = integer(), values = x),
             class = "rle"))
     y <- x[-1L] != x[-n] +incr
     i <- c(which(y | is.na(y)), n)
     structure(list(lengths = diff(c(0L, i)), values = x[i]),
         class = "rle")
}

<quote>
From: David Winsemius <dwinsemius_at_comcast.net>
Date: Sat, 11 Feb 2012 10:08:17 -0500
On Feb 11, 2012, at 10:01 AM, syrvn wrote:

 > Hello,
 >
 > I am struggling with detecting successive digits in a numerical series
 > vector.
 >
 > Here is an example:
 >
 > vec <- c(1, 15, 26, 29, 30, 31, 37, 40, 41)
 >
 > I want to be able to detect 29, 30, 31 and 40, 41.
 >
 > Then, I would like to delete the successive digits from the vector.
 >
 > 1, 15, 26, 29, 37, 40
   vec[ c(TRUE, !diff(vec) == 1) ]
#[1] 1 15 26 29 37 40

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