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</o:shapelayout></xml><![endif]--></head><body lang=FR link=blue vlink=blue><div class=WordSection1><p class=MsoNormal style='text-align:justify'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi,<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='text-align:justify'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I think you can use st_difference bu you have to be </span><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>careful because it will return as many rows as l2 geometries intersect l1 ones. Union them should be a solution but I doubt it is the more performance way :<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>With l2_union as (<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Select l1.id, l1.name, st_union(l2.geom) geom<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> From l1, l2<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Where st_intersects(l1.geom, l2.geom)<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> Group by l1.id, l1.name<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>)<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Select l1.id, l1.name, st_area(st_difference(l1.geom, l2_union.geom))<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>From l1, l2_union<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Where l1.id = l2_union.id<o:p></o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal style='text-align:justify'><span lang=EN-GB style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hugues.<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><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>De :</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> postgis-users-bounces@lists.osgeo.org [mailto:postgis-users-bounces@lists.osgeo.org] <b>De la part de</b> Cedric Duprez<br><b>Envoyé :</b> mercredi 22 mai 2013 08:26<br><b>À :</b> PostGIS Users Discussion<br><b>Objet :</b> Re: [postgis-users] Area of non-intersecting parts of layers<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'>Thanks for the answers.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'>Sorry if I did not explain what I wish correctly.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'>I’m trying to get the area of the difference between l1 and l2 (which is l1 – intersect(l1, l2)).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'>Cedric<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif";color:navy'><o:p> </o:p></span></p><div><div class=MsoNormal align=center style='text-align:center'><hr size=2 width="100%" align=center></div><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>De :</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:postgis-users-bounces@lists.osgeo.org">postgis-users-bounces@lists.osgeo.org</a> [<a href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>] <b>De la part de</b> Nicolas Ribot<br><b>Envoyé :</b> mardi 21 mai 2013 22:23<br><b>À :</b> PostGIS Users Discussion<br><b>Objet :</b> Re: [postgis-users] Area of non-intersecting parts of layers</span><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>Hi,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>I'm too wondering what should be the final result.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>To resolve the case where you also want the the areas of layers 1 geometries that do not contain any layer2 geom, you could use UNION to join the 2 queries:<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>SELECT l1.name1, l2.name2, SUM(ST_Area(ST_Intersection(l1.geom, l2.geom))) / 10000 AS surface_ha<o:p></o:p></p></div><div><p class=MsoNormal>FROM layer1 l1<o:p></o:p></p></div><div><p class=MsoNormal>INNER JOIN layer2 l2 ON ST_Intersects(l1.geom, l2.geom)<o:p></o:p></p></div><div><p class=MsoNormal>GROUP BY 1, 2<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>UNION<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>select l1.name1, '' as name2, sum(st_area(l1.geom)) / 10000<o:p></o:p></p></div><div><p class=MsoNormal>from layer1 l1 <o:p></o:p></p></div><div><p class=MsoNormal>where not exists (<o:p></o:p></p></div><div><p class=MsoNormal> select <a href="http://l2.id">l2.id</a> from layer2 l2 where st_contains(l1.geom, l2.geom)<o:p></o:p></p></div><div><p class=MsoNormal> )<o:p></o:p></p></div><div><p class=MsoNormal>group by 1;<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Nicolas <o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p><div><p class=MsoNormal>On 21 May 2013 22:11, Hugues François <<a href="mailto:hugues.francois@irstea.fr" target="_blank">hugues.francois@irstea.fr</a>> wrote:<o:p></o:p></p><div><div><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hello,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I’m not sure to understand what you are trying to do. Do you want to find the area of polygons from layer 1 which don’t contain any polygon from layer 2 or the difference between l1 and l2 (l1 – intersection(l1,l2)) ?</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hugues.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> </span><o:p></o:p></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>De :</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> <a href="mailto:postgis-users-bounces@lists.osgeo.org" target="_blank">postgis-users-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:postgis-users-bounces@lists.osgeo.org" target="_blank">postgis-users-bounces@lists.osgeo.org</a>] <b>De la part de</b> Cedric Duprez<br><b>Envoyé :</b> mardi 21 mai 2013 18:55<br><b>À :</b> PostGIS Users Discussion<br><b>Objet :</b> [postgis-users] Area of non-intersecting parts of layers</span><o:p></o:p></p></div></div><div><div><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'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Hi all,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif"'>I have 2 layers composed of multipolygons in Postgis 2.0. Each layer contains polygons with a name that is sometime common to several polygons.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB style='font-size:10.0pt;font-family:"Arial","sans-serif"'>When I try to find area of intersections between the 2 layers, no problem with the following query:</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>SELECT l1.name1, l2.name2, SUM(ST_Area(ST_Intersection(l1.geom, l2.geom))) / 10000 AS surface_ha</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>FROM layer1 l1</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>INNER JOIN layer2 l2 ON ST_Intersects(l1.geom, l2.geom)</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>GROUP BY 1, 2</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>ORDER BY 1, 2;</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>OK.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>But I also try to get the area of my layer1 (grouped by name1) that does not contain elements of my layer2.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>I tried with LEFT JOIN, with ST_CONTAINS, without success.</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>Does anyone have an idea on how to write this query?</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>Thanks in advance,</span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB> </span><o:p></o:p></p><p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><span lang=EN-GB>Cedric Duprez</span><o:p></o:p></p></div></div></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>_______________________________________________<br>postgis-users mailing list<br><a href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a><br><a href="http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users" target="_blank">http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users</a><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>