Geoff Canyon wrote:
Bother -- it happened again. First we had repeat for each turning up
faster than the filter command. Now I've done a test on the
following, and it looks like the split command takes not quite twice
as long as repeat for each (when repeat for each is handled the
following way).
function deleteDupes pList -- does _not_ retain sort order
repeat for each line L in pList
put 1 into temp[L]
end repeat
return the keys of temp
end deleteDupes
I wonder if this is because the "split" method used a secondary
delimiter (numtochar(3)) which doesn't exist in the data. (Nothing to do
with the choice of secondaryDelimiter - you need to pick one that isn't
in the data).
So the effort involved in the "split" is
search for next linedelimiter
search within that line for the secondaryDelimiter
(which isn't there, so needs to scan all the way through
each line)
create the array element
(i.e. every character is scanned twice).
In your "repeat for each ... " version, there is only a single search
(for the lineDelimiter), so you're doing basically half as much
searching, plus a little bit of loop overhead.
That fits the data (given huge dollops of hindsight :-), though it is
still surprising and maybe disappointing.
--
Alex Tweedly http://www.tweedly.net
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