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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Hi Tom,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">The d3 library is exactly what I needed. Although d3v4 removed the polygon clipping function, so I am using d3v3.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Cheers,
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Gerard<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> postgis-users [mailto:postgis-users-bounces@lists.osgeo.org]
<b>On Behalf Of </b>Tom van Tilburg<br>
<b>Sent:</b> 07 March, 2017 8:14 AM<br>
<b>To:</b> postgis-users@lists.osgeo.org<br>
<b>Subject:</b> Re: [postgis-users] Efficient Way To Get Voronoi Polygons and Matched Points<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Gerard,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Considering that your points will always be in the heart of your polygons, an ST_Intersects would be faster than ST_Within. 1000 points x 1000 polygons should not be a problem at all in this matter, but you might consider adding a spatial
index to the polygons.<o:p></o:p></p>
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<p class="MsoNormal">On a side note: if your GUI is a web-site, you may consider using D3 voronoi: <a href="https://github.com/d3/d3-voronoi">https://github.com/d3/d3-voronoi</a> It does exactly what you describe.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best, <o:p></o:p></p>
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<p class="MsoNormal"> Tom<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, 2 Mar 2017 at 04:28 Gerard LYNCH <<a href="mailto:gerard.lynch@ericsson.com">gerard.lynch@ericsson.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hello,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I'm using postgis2.3 and ST_VoronoiPolygons.
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I would like to know the best way to do a reverse lookup of sorts to find out which Voronoi polygon maps to which point(s) used in ST_Collect.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Currently I'm looping through each of the input points and doing a ST_Within on each of the Voronoi polygons until I get a match. This can be time consuming when there are 1000
points and 1000 voronoi polygons. I could also do the reverse and loop through each of the Voronoi polygons and fetch points within the polygon but I am wondering if there is a more efficient approach.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Ideally an object that returned something like "Polygon1 => [pointa, pointb], Polygon2 => [pointc]" etc would be preferable.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">My use case is when someone clicks on a Voronoi polygon in my GUI I would like to be able to provide the user with information on the points used to create that polygon.
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Cheers,
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Gerard<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal">_______________________________________________<br>
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<a href="https://lists.osgeo.org/mailman/listinfo/postgis-users" target="_blank">https://lists.osgeo.org/mailman/listinfo/postgis-users</a><o:p></o:p></p>
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