Activity for Jan
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Jan modified a comment on discussion Discussion Forum
On the advice of Angus I did not (yet) put any effort in to group spatially.My data are already organised (spatially) fairly well.So, I'll give a few details first which have to do with my library/organisation.I use a format for a a collection of polygon with holes. In my lingo that is a MultiComplexGon. The data comes as shapefiles, which are read into a single object as before, and then gets sent to the dissolve routine, which puts the data into Path objects, calculates and puts the result back.dissolveloadfactor...
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On the advice of Angus I did not (yet) put any effort in to group spatially.My data are already organised (spatially) fairly well.So, I'll give a few details first which have to do with my library/organisation.I use a format for a a collection of polygon with holes. In my lingo that is a MultiComplexGon. The data comes as shapefiles, which are read into a single object as before, and then gets sent to the dissolve routine, which puts the data into Path objects, calculates and puts the result back.dissolveloadfactor...
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On the advice of Angus I did not (yet) put any effort in to group spatially.My data are already organised (spatially) fairly well.So, I'll give a few details first which have to do with my library/organisation.I use a format for a a collection of polygon with holes. In my lingo that is a MultiComplexGon. The data comes as shapefiles, which are read into a single object as before, and then gets sent to the dissolve routine, which puts the data into Path objects, calculates and puts the result back.dissolveloadfactor...
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On the advice of Angus I did not (yet) put any effort in to group spatially.My data are already organised (spatially) fairly well.So, I'll give a few details first which have to do with my library/organisation.I use a format for a a collection of polygon with holes. In my lingo that is a MultiComplexGon. The data comes as shapefiles, which are read into a single object as before, and then gets sent to the dissolve routine, which puts the data into Path objects, calculates and puts the result back.dissolveloadfactor...
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Hi Angus, I tried smaller groups, but they gave significantly worse results. 1000 was a good start, but also to my surprise, higher was better but 5000 too much. My multithreading does not cover this part, it would have to be nested multithreading, I'm looking into that, as it would help with the largest datasets. Also I haven't spent energy to find out whether the clipping of the groups individually or the clipping of the groupresults takes more time. I hope I can select a smallish sample, but first...
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I've implemented subdivision and tweaked it a bit. In my task the effect is substantial, from about 8 hours to 40 minutes (factor 12). Subdivision is by a factor of the number of items (per class), which varies quite a bit. That worked better than using fixed numbers of polys per subtask, say 1000. I have not preordered the polygons, but they have some ordening stemming from a set of shapefiles covering regular tiles of the whole area. That may also explain why a fractional size worked better than...
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Hi Angus, Was caught up in some socialities ;) I used the PolyTree approach years ago because it gave me the holes. If you say I shouldn't need to do this, I'll have another look. Now I'm converting to 2.0 and have a few loose ends: ReverseSolution(), SimpliFyPolygon(), CleanPolygon(), StrictlySimple() are no longer there, I'm trying to find out whether I really need them, but I'm not comfortable to scrap them; less important but potentially so: ArcTolerance is no longer available and tuning variables...
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Thanks! On Sat, Nov 2, 2019 at 11:03 PM Angus Johnson angusj@users.sourceforge.net wrote: Do you have any reason to believe that the preview version is less correct than the preceding version 4.6.2? (I'm not asking for guarantees, mind you) I'm confident it's still just as robust as version one. However, it's still only beta because there are additional features I hope to address such as removing micro self-intersections related to rounding (which also occur on version 1) and a more complete solution...
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You guys helped me on my way, thanks. I have one remaining question because the code improvements and the speed increase with preview/beta version 2.0 are attractive. Do you have any reason to believe that the preview version is less correct than the preceding version 4.6.2? (I'm not asking for guarantees, mind you) I'll certainly get to work on pre-grouping/input partitioning, probably using the fact that my polygons have calculated stats by the time of clipping, so I can at least use the extents...
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Hi, Thanks for the attention! I require winding number dissolving for this specific case. My basic code is (parts being polygons which may have holes etc. as in shapefile): PolyTree pt; Clipper cl; cl.StrictlySimple(strictlysimple); cl.ReverseSolution(true); for (const auto &p : parts) { const unsigned np = p.npoints(); Path subj; if (subj.capacity()<np) subj.reserve(np); const PuntVector &vertex = p.get_outer().vertices(); for (const auto &pp : vertex) subj.emplace_back(IRound(pp.x * multiplier),...
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I have quite large polygon datasets, order of 1e6 polys which can be clipped in one go, but then take (too much) time. Multicoring is possible, but does not help out enough, even with 16 threads on a Ryzen 2700X. Working with large numbers the expected N2 complexity would have to be - clipped - not to say reduced. Is this assumption of mine correct? My reason for believing that a serious speedup for large datasets is possible, comes from running the desired dissolves on Qgis, but more to the point,...
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You could look at jenks-natural-breaks-in-python-how-to-find-the-optimum-number-of-breaks https://stats.stackexchange.com/questions/143974/jenks-natural-breaks-in-python-how-to-find-the-optimum-number-of-breaks On Sat, Jun 17, 2017 at 12:49 AM, Bryan Andre bryanponce@users.sf.net wrote: Hello, I'm working on classifying grids and I wanted to know if anybody has a script available for the Jenks Natural Breaks method. I'm not a programmer, however I can manage simple python codes and .xml files as...
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Hi, Thanks for a great package. There is a compile warning that may indicate a typo/mistake:...
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Hi, Thanks for a great package. There is a compile warning that may indicate a typo/mistake:...
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Hi, Thanks for a great package. There is a compile warning that may indicate a typo/mistake:...
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Hi, Thanks for a great package. There is a compile warning that may indicate a typo/mistake:...
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This is all correct, but in Windows 10 I was thrown off a bit by the fact that a...
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bug in self.close()
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