[GRASS-dev] Re: bug in Vect_cidx_find_next() ?

[Radim Blazek]

And BTW with the fix, people should get (QGIS/v.digit)
more messages:
"Orphan record was left in attribute table. Delete the record?"

Radim

On 9/29/06, Radim Blazek <radim.blazek at gmail.com> wrote:
> On 9/29/06, Moritz Lennert <mlennert at club.worldonline.be> wrote:
> > Radim Blazek wrote:
> > > Yes,
> > > it seems to be bug, I think that on row 296 in cindex.c
> > > the requested cat should also be checked, not only the type.
> > > But I am tired now, please check it twice.
> >
> > Changing that line into
> >
> > if ( ci->cat[cat_index][0] == cat && ci->cat[cat_index][1] & type_mask )
> >
> > works. Thanks !
> >
> > But I don't really understand how this could happen, as I thought the
> > following lines (286-288) should take care of this before:
> >
> > while ( cat_index > start_index ) {
> >      if ( ci->cat[cat_index-1][0] != cat ) {
> >         break;
>
> No, this goes down to lowes index of this cat because bsearch
> does not return the first item.
>
> To simplify use of cat index in modules I would suggest 2 new functions
> (not tested/compiled):
>
> void Vect_cidx_find_lines ( struct Map_info *Map, int layer, int cat,
>                                  struct ilist *lines )
> {
>       int type, line;
>       struct Cat_index *ci;
>
>       Vect_reset_list ( lines );
>       int field_index = Vect_cidx_get_field_index ( Map, layer );
>       ci = &(Map->plus.cidx[field_index]);
>
>       int idx = Vect_cidx_find_next ( Map, field_index, cat, 0,
>                                   GV_LINES|GV_POINTS, &type, &line );
>
>       if ( idx == -1 ) return;
>
>       do {
>           if ( !(ci->cat[idx][1] & GV_LINES|GV_POINTS)
>                ||  ci->cat[idx][0]  != cat )
>           {
>                break;
>            }
>            Vect_list_append ( lines, ci->cat[idx][2] );
>            idx++;
>        } while (   idx < ci->n_cats );
>        return;
> }
>
> and similarly Vect_cidx_find_areas, then in module:
>
> struct ilist *lines = Vect_new_list();
>
> Vect_cidx_find_lines ( Map, layer, cat, lines );
> for ( i = 0; i < lines->n_values; i++ )
> {
>     line = lines->value[i];
>     Vect_read_line ( Map, Points, NULL, line );
> }
>
> Radim
>
> > So it might actually be a problem in the determination of cat_index
> > which is higher than it should be.
> >
> > But just as you, I'm too tired now to look any deeper into this...
> > ;-)
> >
> > Moritz
> >
> > > Bravo Moritz!
> > >
> > > Radim
> > >
> > > On 9/28/06, Moritz Lennert <mlennert at club.worldonline.be> wrote:
> > >> Hello,
> > >>
> > >> Trying to rework d.vect.chart I am using the Vect_cidx_find_next()
> > >> function.
> > >>
> > >> However, using a map with areas I get behaviour which seems incorrect
> > >> and which I cannot explain.
> > >>
> > >> I have the following category index (result of Vect_cidx_dump(Map,
> > >> stdout)):
> > >>
> > >> .
> > >> .
> > >> [Field 0]
> > >> .
> > >> .
> > >> Field      1  number of unique cats:     589  number of cats:    1185
> > >> number of types: 3
> > >> ------------------------------------------------------------------------------------------
> > >>
> > >>              type |     count
> > >>                 8 |       592
> > >>                 4 |         1
> > >>                64 |       592
> > >>   category | type | line/area
> > >>      11001 |    8 |      1895
> > >>      11001 |   64 |       127
> > >>      11002 |    8 |      1810
> > >>      11002 |   64 |        42
> > >>      11004 |    8 |      1874
> > >>      11004 |   64 |       106
> > >>      11005 |    8 |      1923
> > >>      11005 |   64 |       155
> > >>      11007 |    8 |      1866
> > >>
> > >> etc.
> > >>
> > >> Now, when I launch
> > >>
> > >> Vect_cidx_find_next( Map, field_index=1, cat=11002, type=15,
> > >> start_index=3, &stype, &sid )
> > >>
> > >> it returns 4 and line id=1874.
> > >>
> > >> This is wrong as the fourth item in the index, which does have line id
> > >> 1874, has cat 11004 and not cat 11002. This is confirmed by launching
> > >>
> > >> Vect_cidx_get_cat_by_index ( Map, field_index, 4, &testcat, &testtype,
> > >> &testid)
> > >>
> > >> which returns testcat = 11004.
> > >>
> > >> Am I right in assuming that there is a bug in Vect_cidx_find_next, or am
> > >> I misunderstanding something here ?
> > >>
> > >> I don't have this problem with a pure point file, which only has one
> > >> type:
> > >>
> > >> Field      1  number of unique cats:     589  number of cats:     593
> > >> number of types: 1
> > >> ------------------------------------------------------------------------------------------
> > >>
> > >>              type |     count
> > >>                 1 |       593
> > >>   category | type | line/area
> > >>      11001 |    1 |        97
> > >>      11002 |    1 |        12
> > >>      11002 |    1 |       593
> > >>      11004 |    1 |        76
> > >>      11005 |    1 |       125
> > >>      11007 |    1 |        68
> > >>
> > >>
> > >> So this seems to be linked to the type handling.
> > >>
> > >> Any ideas,
> > >>
> > >> Moritz
> > >>
> > >
> > > _______________________________________________
> > > grass-dev mailing list
> > > grass-dev at grass.itc.it
> > > http://grass.itc.it/mailman/listinfo/grass-dev
> >
> >
>