[R] how to get empty sequence for certain bounds
Hi, I have encountered this problem quite a few times and thought I would ask. Let's say that I have two endpoints, a and b, which are integers. If a = b, I would like to get a:b, but if a b, then numeric(0), for example: myseq(3,5) = 3:5 myseq(3,3) = 3 myseq(3,2) = numeric(0) The operator : just gives decreasing sequences in the latter case, and I could not coax seq into doing this either (of course the documentation is correct, it never claims that I could). Should I just write my own function, or is there a standard R way to do this? Thanks, Tamas __ R-help@stat.math.ethz.ch 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.
Re: [R] how to get empty sequence for certain bounds
On Wed, 2006-11-15 at 11:35 -0500, Tamas K Papp wrote:
Hi,
I have encountered this problem quite a few times and thought I would
ask.
Let's say that I have two endpoints, a and b, which are integers. If
a = b, I would like to get a:b, but if a b, then numeric(0), for
example:
myseq(3,5) = 3:5
myseq(3,3) = 3
myseq(3,2) = numeric(0)
The operator : just gives decreasing sequences in the latter case, and
I could not coax seq into doing this either (of course the
documentation is correct, it never claims that I could). Should I
just write my own function, or is there a standard R way to do this?
Thanks,
Tamas
seq(a, b, length = ifelse(a = b, b - a + 1, 0))
Thus:
a - 3
b - 5
seq(a, b, length = ifelse(a = b, b - a + 1, 0))
[1] 3 4 5
a - 5
b - 3
seq(a, b, length = ifelse(a = b, b - a + 1, 0))
integer(0)
However, is that better than:
a - 3
b - 5
if (a = b) a:b else numeric(0)
[1] 3 4 5
a - 5
b - 3
if (a = b) a:b else numeric(0)
numeric(0)
?
Of course, you could define your own operator:
%:% - function(a, b) {if (a = b) a:b else numeric(0)}
a - 3
b - 5
a %:% b
[1] 3 4 5
a - 5
b - 3
a %:% b
numeric(0)
HTH,
Marc Schwartz
__
R-help@stat.math.ethz.ch 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.
Re: [R] how to get empty sequence for certain bounds
On Wed, 15 Nov 2006, Tamas K Papp wrote: Hi, I have encountered this problem quite a few times and thought I would ask. Let's say that I have two endpoints, a and b, which are integers. If a = b, I would like to get a:b, but if a b, then numeric(0), for example: myseq(3,5) = 3:5 myseq(3,3) = 3 myseq(3,2) = numeric(0) The operator : just gives decreasing sequences in the latter case, and I could not coax seq into doing this either (of course the documentation is correct, it never claims that I could). Should I just write my own function, or is there a standard R way to do this? This has been discussed fairly recently, so see the list archives. myseq - function(m, n) m - 1 + seq_len(max(n-m+1, 0)) looks about right. Note that this is a little strange, as you want to include the left endpoint sometimes and not others. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UKFax: +44 1865 272595 __ R-help@stat.math.ethz.ch 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.
Re: [R] how to get empty sequence for certain bounds
... seq(a, b, length = ifelse(a = b, b - a + 1, 0)) seq(a,b,length = max(0,b-a+1)) seems a bit simpler and more transparent. -- Bert Bert Gunter Genentech Nonclinical Statistics South San Francisco, CA 94404 __ R-help@stat.math.ethz.ch 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.
