Dennis,
I thought the original question on this thread was:
>
Hi list,
Is there a way to use
"repeat for each element thisIndexTerm in listOfTerms"
in reverse order, like in
"repeat with i=number of items of myVar down to 1" ?
Thanks,
JB
>
which has changed to a feature request only later on in the thread.
This feature request would be nice, but doesn't solve the problem
right now.
My answer and there you are right, I should have placed it as a reply
to JB's original question and not to yours, was only to help out and
show some peculiarities of the different solutions proposed, which were:
The first method I mentioned (which you called a speed killer) is
*not* fast at all when the number of lines exceed a certain level
(depending on cpu). And the larger the number of chars in those lines
the slower the performance.
The second method on the contrary doesn't increase processing time in
the same way the first method does and is by far the better solution
for larger amounts of lines and chars.
Greetings,
Wouter
On 28 Jun 2005, at 00:51, Wouter wrote:
Begin forwarded message:
From: Dennis Brown <[EMAIL PROTECTED]>
Date: Mon 27 Jun 2005 23:58:13 GMT+02:00
To: How to use Revolution <[email protected]>
Subject: Re: "repeat for each" in reverse order ?
Reply-To: How to use Revolution <[email protected]>
Wouter,
I'm not sure what this example has to do with the question on the
thread, but you first example is a speed killer. Putting things
in front of a string causes the whole string to be shuffled to
make room for the inserted string. It is a worst case situation --
although I can always come up with a way to make it slower. It
would be faster to use the slower repeat for i=number of lines in
x down to 1 and then put the lines after like your second example.
Splitting into an array is usually a good approach if the repeat
for each construct will not work. However, it does take time to
do the split. A repeat for each could process the whole string in
less time than it takes to split it if a repeat for each fits the
problem.
In your second example, sorting the keys will also take time. You
might be better off with just a simple repeat for i=number of
lines in x down to 1 as the array index. You would have to try it
on your array to see.
Dennis
On Jun 27, 2005, at 4:24 PM, Wouter wrote:
Hi,
Using the following to reverse the order of lines of a field
containing 525605 chars in 14194 lines
reversing by:
on mouseUp
put fld 1 into x
put the long seconds into zap
repeat for each line i in x
put i&cr before tList
end repeat
put the long seconds - zap
put tList into fld 1
end mouseUp
takes > 60 seconds on a slowbook (G4 400 mhz)
reversing by:
on mouseUp
put fld 1 into x
put the long seconds into zap
split x by return
get the keys of x
sort it numeric descending
repeat for each line i in it
put x[i]&cr after tList
end repeat
put the long seconds - zap
put tList into fld 1
end mouseUp
yields around 0.413007 seconds on a slowbook (G4 400 mhz)
(which is not too bad)
The amount of chars and lines has a big influence on the speed in
the first handler,
while in the second handler it has not.
Greetings,
Wouter
On 27 Jun 2005, at 14:40, Dennis Brown wrote:
The repeat for each only goes in forward sequential order
starting at the beginning, except for arrays where the order is
indeterminate.
I have requested a sequential access enhancement to allow for
constructing this type of looping in a more flexible way (like
parallel instantiation, starting at an arbitrary point, and
reverse order), to make it possible to wander all over your data
sequentially with the speed of the repeat for each method.
However, it would be most useful with some improved string
delimiter handling. Bugzilla # 2773
Having a reverse order repeat for each might be up to twice as
slow as the forward version depending on how it is implemented,
because it has to go backwards to the previous delimiter then
forward to pick up the data, though it could pick up the data in
reverse order on the way back. However, even twice as slow
would be much faster than any other method.
Dennis
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