John Fox wrote:
> Dear Wacek,
>
> "Wrong" is a bit strong, I think -- limited to single-pattern characters is
> more accurate.
nothing is ever wrong if seen from an appropriate perspective. for
example, there is nothing wrong in that many core functions in r deparse
some, but not all, of the argument expressions, without any obvious
pattern -- when you get used to it and learn each single case by heart,
it's perfectly correct.
> Moreover, it isn't hard to make the function work with
> multiple-character matches as well:
>
which you probably should have done before posting the flawed version.
> Strsplit <- function(x, split){
> if (length(x) > 1) {
> return(lapply(x, Strsplit, split)) # vectorization
> }
> result <- character(0)
> if (nchar(x) == 0) return(result)
> posn <- regexpr(split, x)
> if (posn <= 0) return(x)
> c(result, substring(x, 1, posn - 1),
> Recall(substring(x, posn + attr(posn, "match.length"),
> nchar(x)), split)) # recursion
> }
>
> On the other hand, your function is much more efficient.
>
just one order of magnitude in my tests. might not be completely fool
proof, though.
vQ
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