Reverse a list
pete at lcsql.com
Fri Feb 13 21:49:53 CET 2015
Glad you figured out the reason for the speed difference.
Not sure if there's a single thread anywhere that talks about repeat loops
but "repeat with" can be orders of magnitude faster than "repeat for" as
you've discovered. In this case there were about 100k lines in the data
and I think I'm right in saying that the time taken to execute a repeat
with loop is directly related to the number of lines being processed.
On Fri Feb 13 2015 at 12:41:14 PM Mike Kerner <MikeKerner at roadrunner.com>
> I must have missed a thread, somewhere. That would be the thread on how LC
> handles loops.
> To recap, doing this sort using an sqlite database (insert the values into
> a table, then sort the table), was taking me almost 40 seconds. Then Pete
> chimed in and had it working in a couple hundred milliseconds.
> The difference? Pete was using a loop of the form
> repeat for each line tLine in theData
> and I was doing a
> repeat with i = 1 to the number of lines in tData
> So, is there some more in-depth discussion of loop forms in LC, somewhere?
> I learned something new, today, because 300x faster is a little bit
> On Thu, Feb 12, 2015 at 9:35 PM, Kay C Lan <lan.kc.macmail at gmail.com>
> > On Fri, Feb 13, 2015 at 3:04 AM, J. Landman Gay <
> jacque at hyperactivesw.com>
> > wrote:
> > > On 2/12/2015 12:54 PM, Peter Haworth wrote:
> > >
> > >>
> > >>> I haven't run any of the LC scripts to do this but if that's true,
> > then
> > >> they don't achieve the original objective of reversing the list.
> > >>
> > >
> > > I don't think it's true. Using LC scripts, the first and last lines
> > > be terminated by a CR and the line count won't change. The first and
> > > lines will have no values but are still terminated by a CR, which is
> > > determines the count.
> > >
> > Jacques right. I should have actually run the scripts rather than just
> > doing it mentally. Because they all add a terminating CR then all is
> > Apologies for confusing the matter.
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