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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Thanks for the answers.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Sorry if I did not
explain what I wish correctly.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;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></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Cedric<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>De :</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
postgis-users-bounces@lists.osgeo.org
[mailto:postgis-users-bounces@lists.osgeo.org] <b><span style='font-weight:
bold'>De la part de</span></b> Nicolas Ribot<br>
<b><span style='font-weight:bold'>Envoyé :</span></b> mardi 21 mai 2013
22:23<br>
<b><span style='font-weight:bold'>À :</span></b> <st1:PersonName w:st="on">PostGIS
Users Discussion</st1:PersonName><br>
<b><span style='font-weight:bold'>Objet :</span></b> Re: [postgis-users]
Area of non-intersecting parts of layers</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Hi,<o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>I'm too wondering what should be the final result.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>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></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>SELECT l1.name1, l2.name2, SUM(ST_Area(ST_Intersection(l1.geom,
l2.geom))) / 10000 AS surface_ha<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>FROM layer1 l1<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>INNER JOIN layer2 l2 ON ST_Intersects(l1.geom, l2.geom)<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>GROUP BY 1, 2<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>UNION<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>select l1.name1, '' as name2, sum(st_area(l1.geom)) / 10000<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>from layer1 l1 <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>where not exists (<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> select <a href="http://l2.id">l2.id</a> from layer2 l2
where st_contains(l1.geom, l2.geom)<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> )<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>group by 1;<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Nicolas <o:p></o:p></span></font></p>
</div>
</div>
<div>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>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></span></font></p>
<div link=blue vlink=purple>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'>Hello,</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;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></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'>Hugues.</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 color="#1f497d" face=Calibri><span style='font-size:11.0pt;font-family:
Calibri;color:#1F497D'> </span></font><o:p></o:p></p>
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<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><font
size=2 face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;font-weight:
bold'>De :</span></font></b><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'> <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><span style='font-weight:bold'>De la part de</span></b> Cedric Duprez<br>
<b><span style='font-weight:bold'>Envoyé :</span></b> mardi 21 mai 2013
18:55<br>
<b><span style='font-weight:bold'>À :</span></b> <st1:PersonName w:st="on">PostGIS
Users Discussion</st1:PersonName><br>
<b><span style='font-weight:bold'>Objet :</span></b> [postgis-users] Area
of non-intersecting parts of layers</span></font><o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span style='font-size:12.0pt'> <o:p></o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Hi all,</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> </span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>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></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=2 face=Arial><span lang=EN-GB style='font-size:10.0pt;font-family:Arial'>When
I try to find area of intersections between the 2 layers, no problem with the
following query:</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>SELECT
l1.name1, l2.name2, SUM(ST_Area(ST_Intersection(l1.geom, l2.geom))) / 10000 AS
surface_ha</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>FROM
layer1 l1</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>INNER
JOIN layer2 l2 ON ST_Intersects(l1.geom, l2.geom)</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>GROUP
BY 1, 2</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>ORDER
BY 1, 2;</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>OK.</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>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></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>I tried
with LEFT JOIN, with ST_CONTAINS, without success.</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>Does
anyone have an idea on how to write this query?</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>Thanks
in advance,</span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'> </span><o:p></o:p></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><font
size=3 face="Times New Roman"><span lang=EN-GB style='font-size:12.0pt'>Cedric
Duprez</span><o:p></o:p></font></p>
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<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
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