improve performance of removerepeatedpoints(multipoint) #609
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kalenikaliaksandr
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Komzpa
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liblwgeom/lwgeom.c
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| POINT2D ptj, pti; | ||
| getPoint2d_p(mpt->geoms[i]->point, 0, &pti); | ||
| getPoint2d_p(mpt->geoms[j]->point, 0, &ptj); | ||
| if (distance2d_sqr_pt_pt(&ptj, &pti) > tolsq) |
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This is not enough - for instance, in the square in the center of this image there can possibly be three points within the distance.
Your method can still be a special case for tolerance=0, just plug back in old one :)
I see three big options how to implement this:
I. via double grid snap:
- snap to grid of size = tolerance
- check all the ones in the same bucket if they are the same
- snap to grid of size = tolerance with a shift of 0.5
- check all the ones in the same bucket if they are the same
II. double-sorting with window tracking:
- order by X
- iterate through list, look for duplicates back in the list until X is within tolerance
- order by Y
- iterate through list, look for duplicates back in the list until Y is within tolerance
III. tree
- build a tree
- while building a tree insertions, skip inserting points that have a point in tree within radius.
Komzpa
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Apr 19, 2021
liblwgeom/lwgeom.c
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| lwgeom_calculate_gbox((LWGEOM *)p2, &b2); | ||
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| uint64_t h1, h2; | ||
| h1 = gbox_get_sortable_hash(&b1, 0); |
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will probably be neater to refactor it to also allow points (it casts box back into a point internally and that piece can be isolated), and pass original srid
Komzpa
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|
merged 423b519 |
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