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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>While you guys are grokking the code, perhaps you can figure out what is causing this test to fail once in a while.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Fails more on 32-bit more than 64-bit. Now I saw a similar failure on travis, might be Darafei's specially added testing sauce triggering that one </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><a href="https://trac.osgeo.org/postgis/ticket/3700">https://trac.osgeo.org/postgis/ticket/3700</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Anyway this failure is not repeatable unfortunately<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Last one happened just recently on winnie's 64-bit run.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><a href="https://trac.osgeo.org/postgis/ticket/3700#comment:18">https://trac.osgeo.org/postgis/ticket/3700#comment:18</a><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Darafei if you want to experiment with logbt as you mentioned in that ticket +1 from me for 2.5 branch. Don't wait for any more +1s, just do and ask for forgiveness later if anyone screams </span><span style='font-size:11.0pt;font-family:Wingdings;color:#1F497D'>J</span><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'>Regina<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='margin-left:.5in'><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-devel [mailto:postgis-devel-bounces@lists.osgeo.org] <b>On Behalf Of </b>Tom van Tilburg<br><b>Sent:</b> Thursday, December 28, 2017 5:21 PM<br><b>To:</b> PostGIS Development Discussion <postgis-devel@lists.osgeo.org><br><b>Subject:</b> Re: [postgis-devel] Bias in ClusterKmeans<o:p></o:p></span></p><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><div><div><p class=MsoNormal style='margin-left:.5in'>I was just looking at that code and trying to wrap my head around the rationale. Why a diagonal seed?<o:p></o:p></p></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>A grid would indeed solve my example but I have more irregular input data. <o:p></o:p></p></div><p class=MsoNormal style='margin-left:.5in'>Would a quick & dirty solution be to spread K points randomly in the convex-hull of the the input set?<o:p></o:p></p><div><div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><p class=MsoNormal style='margin-left:.5in'>Your proposed strategy looks much more stable than the current and as far as I can grasp it would give denser seeding where there is higher density of geometries. I wonder though why it wouldn't be enough to just randomly pick points from the input set, apart from having a different outcome every time. <o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>Tom<o:p></o:p></p></div><div><div><p class=MsoNormal style='margin-left:.5in'><br>On Thu, Dec 28, 2017 at 10:47 PM, Darafei "Komяpa" Praliaskouski <<a href="mailto:me@komzpa.net" target="_blank">me@komzpa.net</a>> wrote:<o:p></o:p></p><div><div><div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in'><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><div><p class=MsoNormal style='margin-left:.5in'>Tom, the line of code that does the diagonal seeding is this:<o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-left:.5in'><a href="https://github.com/postgis/postgis/blob/svn-trunk/liblwgeom/lwkmeans.c#L187" target="_blank">https://github.com/postgis/postgis/blob/svn-trunk/liblwgeom/lwkmeans.c#L187</a> <o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>At the very least to fix your case it may need to seed in a grid, so you need to make it two loops for row and column and estimate range for them from min/max height and width.<o:p></o:p></p></div></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></blockquote></div></div></div></div></div></div></div></div></body></html>