Gabor Grothendieck wrote:
> For the problem at hand I think I would use your solution
> which is both easily understood and fastest. On the
> other hand the tapply based solutions are coordinate
> free (i.e. no explicit mucking with indices) and readily
> generalize to more than 2 groups -- just replace [^pq] with
> [^pqr], say.
>
>
for sure, mine was optimized towards the case, not towards generalizability.
the gsubfn one is a loser, though.
but the first one *is* easily generalizable, e.g.,
letters = "pqrs"
sapply(sprintf("^[^%s]*%s", letters, unlist(strsplit(letters,
split=""))), grep, x=x, value=TRUE)
while an order of magnitude faster than the tapply ones.
vQ
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