[mkgmap-dev] Possible problem with global search index since r3875

Sat Apr 8 13:56:25 BST 2017

Hi Steve,

so I guess that I should revert some of the changes made in Mdr7 to make this work again (presuming that
the order produced by r3449 was okay for both variants (--x-split-name-index  on/off).
At the moment we have different versions in trunk and in the branch, and both might not work when this
feature is used.

Another point is the question how to sort/de-duplicate the index. I noticed that with option --x-split-name-index
the results shown in MapSource are sorted a bit unexpected.
Example: In Switzerland I found road names like
'14 Hauptstrasse' and nearby one named '13/14 Hauptstrasse'
When I type "14 Hau"  I want to find both entries, but I prefer to see '14 Hauptstrasse' first (topmost).
This depends on how we sort, maybe also on the order in which the names appear in the *.img files.

I continue experimenting with all this new knowledge later.

Gerd
________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Steve Ratcliffe <steve at parabola.me.uk>
Gesendet: Samstag, 8. April 2017 14:10:07
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] Possible problem with global search index since r3875

Hi

> I've just noticed that I may have introduced a problem with r3875.
> Road names containing special characters 0x1e and 0x1f are treated different now. I am not
> sure where those characters appear in names. I think they are used to store so called double byte

0x1e is a prefix separator and 0x1f a suffix separator.

They are used instead of a space in street names to separate the
main part of the name from Chemin, Rue, Road, Avenue etc.

If I use ']' for 0x1e and '[' for 0x1f, then streets can be written
as:

   Rue]Nicolo
   Chemin de]Pierre Froide
   Fernrodder[Strasse
   Street Lane[Road

This also affects searching in mapsource and the prefix/suffix parts
seem to be ignored.

For example if I want to search for 'Street Lane Road' (its a real
name!)
I type the letters 'street lane' and the full name is shown in the dropdown.
But if I add the 'r' as in 'street lane r', then it no longer
matches and the next matching name is shown in the dropdown, which
happens to be 'Street Lane Roundabout'.

There is also the sections in the index mdr30/31 and mdr32/33 which
are simple lists of prefixes and suffixes.  I do not know how they
are used.

In mapsource you have to pick from the dropdown list.  So to select
our favourite French road 'Chemain de Pierre Froide' you have to type
'pierre fr...' and select.  Starting from 'Chemain ...' does not
get you anywhere even if you type the whole name.  In BaseCamp,
you can type the whole name, and although it also will not show
in the dropdown, it will allow you to enter it and it will find it.

..Steve
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