On Oct 28, 2011, at 4:08 AM, Samir Benzerfa wrote:
Hi David,
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 correct. Fully tested solutions are provided when complete
example code displaying the complexity of the problem is offered. If I
had been posed a question that actually had a "gap" then the first
thing I would have tried would be to construct a logical test for the
condition under scrutiny and apply it to the indexing system. Using
you example below (which is deficint in not having more than one
column with hits)
> str(with(runs, table(values, lengths)))
'table' int [1:7, 1:2] 3 1 1 2 2 1 2 1 0 0 ...
- attr(*, "dimnames")=List of 2
..$ values : chr [1:7] "1" "2" "3" "4" ...
..$ lengths: chr [1:2] "1" "3"
> xtbl <- with(runs, table(values, lengths))
> attr(xtbl, "dimnames")$lengths
[1] "1" "3"
> which( as.numeric( attr(xtbl, "dimnames")$lengths) >=2 )
[1] 2
You could have just used that value, but I think it would be useful to
test it with an example that has another run length > 2 including one
that is "disjpoint"
> x=c(1,3,4,9,1,9,1,5,4,5,2,1,1,1,6, 1,1,1,1,1)
> xtbl <- with(rle(x), table(values, lengths))
> xtbl
lengths
values 1 3 5
1 3 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
> which( as.numeric( attr(xtbl, "dimnames")$lengths) >=2 )
[1] 2 3
So this is a better tested solution:
> xtbl["1", which( as.numeric( attr(xtbl, "dimnames")$lengths) >=2 )]
3 5
1 1
--
David.
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:dwinsem...@comcast.net]
Gesendet: Donnerstag, 27. Oktober 2011 16:44
An: Duncan Murdoch
Cc: Samir Benzerfa; r-help@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
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