[R] The end of Matlab

hadley wickham h.wickham at gmail.com
Fri Dec 12 19:06:16 CET 2008

>> Oh yes, that's a good point.  But wouldn't the following do the job?
>> "&.selector" <- function(a, b) {
>>  function(n) a(n) & b(n)
>> }
>> or
>> "&.selector" <- function(a, b) {
>>  function(n) intersect(a(n), b(n))
>> }
>> depending on whether selectors return logical or numeric vectors.
>> Writing functions for | and ! would be similarly easy.  Or am I
>> missing something?
> No, I think those definitions would be fine, but I'd be concerned about
> speed issues if we start messing with primitives.

Speed or expressiveness: pick one? ;)  People could always use the
regular subsetting mechanisms if they want the best speed - any
changes to support selectors wouldn't affect the speed of the other
methods of subsetting, would they?

> While we're at it, we might as well do the same sort of thing for :, and
> define a selector named end, and then 3:end would give a selector from 3 to
> the end, which brings us back to the original question.  So it's not nearly
> as intrusive as I thought it would be.

3:end() do you mean?  Or do you mean extending seq so that it uses
unevaluted input?



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