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
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David Winsemius, MD
West Hartford, CT
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and provide commented, minimal, self-contained, reproducible code.
