[R] question R regarding consecutive numbers

[William Dunlap]

Are you looking for something like the following?  ifactor()
is like factor but assumes that x is integral and that levels
should be {1, 2, ..., max(x)} with no gaps.

> x <- c(1,3,4,9,1,9,1,5,4,5,2,1,1,1,6)
> ifactor <- function(x, levels=seq_len(max(0, x, na.rm=TRUE))) factor(x, levels=levels)
> with(rle(x), table(ifactor(values), ifactor(lengths)))
   
    1 2 3
  1 3 0 1
  2 1 0 0
  3 1 0 0
  4 2 0 0
  5 2 0 0
  6 1 0 0
  7 0 0 0
  8 0 0 0
  9 2 0 0

Also note that tbl["2","3"] does not mean the same as tbl[2,3],
although if you use the ifactor function as above they will refer
to the same element.

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 Samir Benzerfa
> Sent: Friday, October 28, 2011 12:35 AM
> To: 'David Winsemius'; 'Duncan Murdoch'
> Cc: r-help at r-project.org
> Subject: Re: [R] question R regarding consecutive numbers
> 
> In the general case, there is still a gap in your solution >sum( tbl["1",
> 2:ncol(tbl)] ). This solution refers to a specific column number (here:
> column number 2) and not to the actual length of the run, doesn't it? That
> is, in this simple example the column number 2 actually corresponds to the
> length "2", but this must not be the case in general. For instance if there
> is no run of length "2" but only of length "1" and "3", the column number 2
> will refer to length "3" (try it with the new vector below). I realized this
> problem when applying your solution to a much more extended vector. So, the
> problem is that I would have to check manually whether the column number
> really corresponds to the length of runs. A possible solution would be to
> force R to show all the lengths from 1:ncol even if there is no run of some
> lengths in-between and just fill the whole column with zero's.
> 
> > x=c(1,3,4,9,1,9,1,5,4,5,2,1,1,1,6)
> 
> Any ideas how to solve this problem?
> 
> Cheers, S.B.
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: David Winsemius [mailto:dwinsemius at comcast.net]
> Gesendet: Donnerstag, 27. Oktober 2011 16:44
> An: Duncan Murdoch
> Cc: Samir Benzerfa; r-help at r-project.org
> Betreff: Re: [R] question R regarding consecutive numbers
> 
> 
> On Oct 27, 2011, at 9:21 AM, Duncan Murdoch wrote:
> 
> > On 27/10/2011 8:43 AM, Samir Benzerfa wrote:
> >> Hi  everyone
> >>
> >>
> >>
> >> Do you know about any possibility in R to check for consecutive
> >> numbers in
> >> vectors? That is, I do not only want to count the number of
> >> observations in
> >> total (which can be done table(x)), but I also want to count for
> >> instance
> >> how many times that vector contains a certain number consecutively.
> >>
> >>
> >>
> >> For example in the following vector x the number "1" appears 7 times.
> >> However, I want to check for instance how many times two
> >> consecutive 1's
> >> appear in the vector, which would actually be two times the case in
> >> the
> >> below vector.
> >>
> >>
> >>
> >> >  x=c(1,1,3,4,9,1,9,1,5,4,5,2,1,1,1,6)
> >>
> >>
> >>
> >> Any ideas for this issue?
> >
> > How about this?
> >
> > > runs <- rle(x)
> > > with(runs, table(values, lengths))
> 
> And to go even a bit further, the table function returns a matrix
> which can be addressed to yield the specific answer requested:
> 
>   with(runs, table(values, lengths))["1",2]
> [1] 1  # m=number of exactly runs if length 2
>  > sum( tbl["1", 2:ncol(tbl)] )
> [1] 2  # number of runs of length two or more.
> 
> 
> --
> David
> 
> >
> 
> >     lengths
> > values 1 2 3
> >     1 2 1 1
> >     2 1 0 0
> >     3 1 0 0
> >     4 2 0 0
> >     5 2 0 0
> >     6 1 0 0
> >     9 2 0 0
> >
> > Duncan
> >
> > ______________________________________________
> > 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
> 
> ______________________________________________
> 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.