[mkgmap-dev] Remove-obsolete on line with matching ends

Thu Jun 17 12:06:56 BST 2021

Hi Gerd

The previous loop is reasonable, returning the correct count of
duplicate nodes, although in the case of (a b c b a) it tests for c ==
c.
The loop/subList correctly handled the major cases:
 (a b c p1 p2 c b a) > (a b c p1 p2 c)
 (a b c p1 ... pn c b a) > (a b c p1 ... pn c)
and:
 (a b c b a) > (a b c)
where need to remove lenDup -1 nodes from the end.

However, in the case (a b c c b a), need to remove lenDups

Ticker

On Thu, 2021-06-17 at 10:39 +0000, Gerd Petermann wrote:
> Hi Ticker,
> 
> the thing is: If the previous loop allows duplicate nodes that should
> be fixed in general, not just for this very special case.
> 
> Gerd
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Donnerstag, 17. Juni 2021 12:27
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Remove-obsolete on line with matching ends
> 
> Hi Gerd
> 
> It might never happen - depends on the behaviour of other filters,
> OSM
> data, etc, etc. Fixing it is trivial and will save other programmer's
> time when they look at the code and wonder what happens in the
> various
> cases and spot this case leaving a duplicate point and come up with a
> fix again.
> 
> Ticker
> 
> On Thu, 2021-06-17 at 09:57 +0000, Gerd Petermann wrote:
> > Hi Ticker,
> > 
> > that's clear. I just don't see in what situation this can happen.
> > 
> > Gerd
> > 
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> > von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> > Gesendet: Donnerstag, 17. Juni 2021 11:53
> > An: Development list for mkgmap
> > Betreff: Re: [mkgmap-dev] Remove-obsolete on line with matching
> > ends
> > 
> > Hi Gerd
> > 
> > For a b c c b a, lenDup is 3, then, without my patch, it does
> > subList(0, size()+1-lenDup), ie subList(0, 4), so resulting in a b
> > c
> > c
> > 
> > Ticker
> > 
> > 
> > On Thu, 2021-06-17 at 05:33 +0000, Gerd Petermann wrote:
> > > Hi Ticker,
> > > 
> > > do you have an example where this patch changes something? I
> > > think
> > > it
> > > would mean that the previous loop doesn't work.
> > > 
> > > Gerd
> > > 
> > > ________________________________________
> > > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im
> > > Auftrag
> > > von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> > > Gesendet: Mittwoch, 16. Juni 2021 12:41
> > > An: mkgmap development
> > > Betreff: [mkgmap-dev] Remove-obsolete on line with matching ends
> > > 
> > > Hi Gerd
> > > 
> > > Here is a slight enhancement to low-res-opt RemoveObsolete. It is
> > > possible that this case (a b c c b a) will never happen because
> > > "c"
> > > will probably be de-duped.
> > > 
> > > Ticker
> > > 
> > > _______________________________________________
> > > mkgmap-dev mailing list
> > > mkgmap-dev at lists.mkgmap.org.uk
> > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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