Split a numeric vector into continuous chunks in R

Question

If I have a numeric vector [1 2 3 4 7 8 9 10 15 16 17], how can I split it so that I have multiple vectors returned that separate the continuous elements of that vector? I.e. [1 2 3 4] [7 8 9 10] [15 16 17]. I've found an answer of how to do this in matlab, but I only use R.

Thanks.

Some alternatives here: http://stackoverflow.com/questions/8400901/detect-intervals-of-the-consequent-integer-sequences — Henrik, Aug 29 '13 at 10:41

alexwhan · Accepted Answer · 2013-08-29T10:41:55.933

6

Here's another alternative:

vec <- c( 1, 2, 3, 4, 7, 8, 9, 10, 15, 16, 17 )
split(vec, cumsum(seq_along(vec) %in% (which(diff(vec)>1)+1)))
# $`0`
# [1] 1 2 3 4
# 
# $`1`
# [1]  7  8  9 10
# 
# $`2`
# [1] 15 16 17

edited Aug 29 '13 at 10:41

answered Aug 29 '13 at 10:36

alexwhan

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This answer is incorrect from what the OP has shown. But seeing that the OP has accepted this answer, you seem to have read his mind! ;) – Arun Aug 29 '13 at 10:39
@Arun, excellent point, don't know how I stuffed that up... corrected now! – alexwhan Aug 29 '13 at 10:42
Apologies - I was a little trigger happy here. I thought that this was the correct solution, but as arun points out, it's not quite what I was asking. Thanks anyway! – user2728808 Aug 29 '13 at 10:44
@user2728808 Fair enough - sorted out now – alexwhan Aug 29 '13 at 10:46
1

Ok, the OP wants the vector to be split into continuous runs, so this is (the only) correct answer. +1 – Simon O'Hanlon Aug 29 '13 at 10:47
@Arun, I think in your example the OP would like to end up with a list of six vectors of length 1 – alexwhan Aug 29 '13 at 10:49
@alexwhan, dint read the "continuous elements of the vector" part good enough. +1, nice answer! – Arun Aug 29 '13 at 10:50
Thanks @alexwhan, this is now perfect. Thanks to all for contributing. Very helpful! – user2728808 Aug 29 '13 at 10:51

score 0 · Answer 2 · answered Aug 29 '13 at 20:38

0

Another option:

split(vec, cummax(c(1,diff(vec))))

Result

$`1`
[1] 1 2 3 4

$`3`
[1]  7  8  9 10

$`5`
[1] 15 16 17

answered Aug 29 '13 at 20:38

Ferdinand.kraft

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Split a numeric vector into continuous chunks in R

2 Answers2

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