Eric Chatonet wrote:
Hi Richard,
I think the speed depends on the filter complexity.
For instance:
on mouseUp
repeat 100000
if random (2) = 1 then put "zaz" & cr after tList
else put "zbz" & cr after tList
end repeat
-----
put the milliseconds into tStart1
filter tList with "*a*"
put the milliseconds - tStart1 into tResult1
-----
put the milliseconds into tStart2
repeat for each line tLine in tList
if "a" is in tList then put tLine & cr after tNewList
end repeat
delete char -1 of tNewList
put the milliseconds - tStart2 into tResult2
-----
put "Filter: " && tResult1 & cr &"Repeat:" && tResult2
end mouseUp
Results -
Filter: 41
Repeat: 117
To get cleaner results I think the second test's "is in tList" should be
"is in tLine", which also cuts execution time down dramatically.
But the central point remains: with a small number of criteria the
filter command does a fine job compared to repeat loops, but for complex
criteria (in my app it's rare that we'll ever have fewer than three
distinct comparisons) "repeat for each" does well.
Another advantage of "repeat for each" is that it allows "or" in additon
to "and", which would require multiple passes with "filter", and makes
it easy to structure comparisons using parentheses to control the order
of precedence.
For the moment I'm sticking with the repeat loop for the situation I'm
currently using it in, but it's good to know that filter is quick for
simple searches.
--
Richard Gaskin
Fourth World Media Corporation
___________________________________________________________
[EMAIL PROTECTED] http://www.FourthWorld.com
So may be we have to choose the right method according to the context.
Two cents that do not make life easier :-)
Le 12 juil. 05 à 22:26, Richard Gaskin a écrit :
I figured the filter command would carry at least some overhead for
its convenience, but I had no idea how much!
I wrote the test below to compare it with walking through a list line
by line, and the results were surprising:
on mouseUp
put fwdbCurTableData() into s -- gets 10,800 lines of
-- tab-delimited data
--
-- Method 1: filter command
--
put format("*a*\t*r*\tr\t*\t*\t*\t*\t*") into tFilter
put s into result1
put the millisecs into t
filter result1 with tFilter
put the millisecs - t into t1
--
--
-- Method 2: repeat for each
--
set the itemdel to tab
put the millisecs into t
repeat for each line tLine in s
if item 1 of tLine contains "a" \
AND item 2 of tLine contains "r"\
AND item 3 of tLine is "r" then
put tLine&cr after result2
end if
end repeat
delete last char of result2
put the millisecs - t into t2
--
put result1 into fld "result"
put result2 into fld "result2"
--
put "Filter: "&t1 &cr& "Repeat: "&t2
end mouseUp
Results -
Filter: 745
Repeat: 40
Did I miss something, or am I just seeing the penalty for the filter
command's generalization?
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