[R] help with rle function on paired data

[William Dunlap]

  > ldiff <- function(x)c(TRUE, x[-1]!=x[-length(x)]) # "logical" diff function
  > d[ldiff(d$DataValue), ]
    ElpsdTime DataValue
  1         0         1
  4        90         2
  6       150         3
  7       180         2
  8       210         3

ldiff does the first half of what rle does.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of Steve E.
> Sent: Friday, June 08, 2012 2:33 PM
> To: r-help at r-project.org
> Subject: [R] help with rle function on paired data
> 
> Dear R Community - I hope you might be able to provide some guidance
> regarding the use of the rle function. I have a set of time-series data
> where a measured value is recorded every 30 seconds after the start of an
> experiment. Many of the measured values repeat and I am interested only in
> the values when there is a change. If I turn the measured values into a
> vector, the rle function works perfectly for this but I need also the
> corresponding time of the value and I am not sure how to use rle on paired
> data. Below is a brief example to help explain the problem. I thank you in
> advance for any assistance you might be able to provide. Regards, Steve
> 
> Original dataset:
> 
> ElpsdTime, DataValue
> 0, 1
> 30, 1
> 60, 1
> 90, 2
> 120, 2
> 150, 3
> 180, 2
> 210, 3
> 240, 3
> .
> .
> 
> Desired dataset:
> 
> ElpTime	DataValue
> 0, 1
> 90, 2
> 150, 3
> 180, 2
> 210, 3
> .
> .
> 
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/help-with-rle-function-on-
> paired-data-tp4632856.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.