[Rcpp-devel] Rcpp "version" of R's match function

[Hadley Wickham]

>> PS.  Would you be interested in a set of R functions that from a quick
>> skim of the R sources that I think could be much much faster if
>> implemented in Rcpp?
>
> Sure. Time I have available will decide what I do of the list ^^.

Here's the list:

    rowsum.default (C)?
    findInterval (C)?
    tapply (R: split + lapply)
    median.default
    cut.default?
    duplicated.data.frame
    rank?
    rle (R, 3 copies) ?
    %in%
    range.default

range.default is particularly bad because range uses internal S3
dispatch, it creates a copy of the vector if na.rm = TRUE, and it
calls min and max separately.  I suspect it should be possible to
implement %in% more efficiently rather than match. Some of the others
(findInterval, cut, median) should be easy to implement with the STL,
but might not be that much faster than the existing C code.

Hadley

-- 
RStudio / Rice University
http://had.co.nz/