<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>Hi,</div>
<div>I tried measure='1' and serveral variations including ' and ", but none of them returns other than NULL.</div>
<div> </div>
<div>measure is an integer field, so measure=1 in SQL would be ok, I guess.</div>
<div> </div>
<div>Regards,</div>
<div>Roland</div>
<div> </div>
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<div style="margin:0 0 10px 0;"><b>Gesendet:</b> Freitag, 20. August 2021 um 11:48 Uhr<br/>
<b>Von:</b> "Phil Wyatt" <phil@wyatt-family.com><br/>
<b>An:</b> "'Roland Spielhofer'" <rspiel@gmx.net>, "'qgis-user'" <qgis-user@lists.osgeo.org><br/>
<b>Betreff:</b> RE: [Qgis-user] Length of lines in polygon depending on attribute</div>
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<p class="MsoNormal"><span>Hi Roland,</span></p>
<p class="MsoNormal"><span> </span></p>
<p class="MsoNormal"><span>I am assuming measure is a field name so what happens if you try measure=’1’?</span></p>
<p class="MsoNormal"><span> </span></p>
<p class="MsoNormal"><span>Cheers - Phil</span></p>
<p class="MsoNormal"><span> </span></p>
<p class="MsoNormal"><span> </span></p>
<p class="MsoNormal"><span> </span></p>
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<p class="MsoNormal"><b><span>From:</span></b><span> Qgis-user <qgis-user-bounces@lists.osgeo.org> <b>On Behalf Of </b>Roland Spielhofer<br/>
<b>Sent:</b> Friday, 20 August 2021 7:20 PM<br/>
<b>To:</b> qgis-user <qgis-user@lists.osgeo.org><br/>
<b>Subject:</b> [Qgis-user] Length of lines in polygon depending on attribute</span></p>
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<p class="MsoNormal"> </p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Hi,</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">I have a polygon layer and a line layer.</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">I would like to update a field in the polygon layer with the length of the lines in each polygon that have a certain value in an attribute.</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">I thought I use the field calculator and the aggregate function but I did not succeed.</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">What I have now is:</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">aggregate( layer:='line_layer', aggregate:= 'sum', expression:='length', filter:='measure=1')</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">which returns NULL</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">In the line layer there is an attribute 'length' that already holds the length of the element.</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">I only want the lines that have the attribute "measure=1".</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Any help appreciated!</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Regards,</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;">Roland</span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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<p class="MsoNormal"><span style="font-size: 9.0pt;font-family: Verdana , sans-serif;"> </span></p>
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