[R] Count matches of a sequence in a vector?
Jeff Brown
dopethatwantscash at yahoo.com
Wed Apr 21 20:28:54 CEST 2010
Phil's algorithm is a good one, unless you're worried about optimizing for
speed. It makes N * M comparisons, where N is the length of the first
vector and M is the length of the second. Explicitly iterating through the
longer vector, you could reduce the number of comparisons to M. As is often
the case, here there's a tradeoff between human effort and computer effort.
OTOH, because explicit iteration incurs higher interpretation costs in R, it
could conceivably be that Phil's algorithm performs faster. I don't know.
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