On Sep 21, 2010, at 6:31 AM, Lorenzo Isella wrote:
Dear All,
Consider a simple example
a<-c(1,4,3,0,4,5,6,9,3,4)
b<-c(0,4,5)
c<-c(5,4,0)
I would like to be able to tell whether a sequence is contained (the
order of the elements does matter) in another one e.g. in the
example above, b is a subsequence of a, whereas c is not. Since the
order matters, I cannot treat the sequences above as sets (also,
elements are repeated).
Does anyone know a smart way of achieving that?
> grep(paste(c, collapse="#"), paste(a, collapse="#"))
integer(0)
> grep(paste(b, collapse="#"), paste(a, collapse="#"))
[1] 1
Looking at that output I am wondering if you might need to also put
markers at the ends of the arguments.
> grep(paste("#",b,"#", collapse="#"), paste("#",a,"#", collapse="#"))
[1] 1
# To prevent a match like c(1,2,3) with c(101,2,303).
There is also an istrings package in the BioConductor repository that
provides more extensive string matching facilities.
--
David Winsemius, MD
West Hartford, CT
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