[ You guys probably all know this already, and I had just missed it up
till now ....]
Any time speed of looping through a data structure is mentioned, the
first thing anyone says is
Use
repeat for each line tLine of tData
doSomeThingWith tLine
because it is much faster than
repeat with tIndex = 1 to the number of lines in tData
doSomeThingWith line tIndex of tData
I just realized tonight that you can do
put the number of lines in tData into tNumLines
split tData by CR
repeat with tIndex = 1 to tNumLines
doSomeThingWith tData[tIndex]
(and later combine it again if needed)
While this is nowhere near as fast as the "repeat for", it is better (by
one or two orders of magnitude) than the "line tIndex of tData" version
- fast enough that algorithms which I had rejected because of the
slowness of "line tIndex of tData" can be worth considering again.
In particular - one obvious approach to the "common vs non-common lines"
problem would be to sort each list, and then step through them
"together", using an index into each one. This isn't a good approach in
Rev - because of the high cost of using "line tIndex of tData" - but
using the split and tData[tIndex] makes it feasible. In fact, I found
that my first idea of using the two arrays and 'union' is no faster than
doing the following
(note "ZZZZZ is assumed to be after all possible lines, and is added to
ease the loop termination case)
put fld "Field" & cr & "ZZZZZZZZZZ" into t1
put fld "Field" & cr & "test line" & cr & "ZZZZZZZZZZ" into t2
put the millisecs into tStart
put 1 into i2
put the number of lines in t2 into limit2
sort t1
sort t2
split t2 by CR
put t2[1] into L2
repeat for each line L1 in t1
repeat while L2 < L1
add 1 to i2
put t2[i2] into L2
end repeat
if L2 = L1 then
-- put L1 & cr after tBoth
add 1 to i2
put t2[i2] into L2
else
-- put L1 & cr after t1only
end if
end repeat
if i2 < limit2 then
repeat with i = i2 to limit2-1
put t2[i] & cr after t2only
end repeat
end if
put "loop" && the millisecs - tStart & cr after msg
P.S. I tried hard to break every one of Jerry's recommendation about
variable naming as described in his excellent tutorial from the
"Conference" session; if you haven't already downloaded and read that
stack, you should. It *might* just stop you from writing such ugly code
as I did above - but my old Fortran habits just keep coming back :-)
--
Alex Tweedly http://www.tweedly.net
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