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<div class="moz-cite-prefix">Hi Alessandro, Matthias<br>
<br>
>Is there no requirement for multi types?<br>
<br>
Afaik, the problem for f-tools are not the multi types, but only
the geometry collections (containing geometries with different
shape type). In my experience, if geos returns a geometry
collection, it usually contains one 'expected' geometry and the
others are slivers (@strk, please correct me if wrong).<br>
<br>
>Based on what indicator should be chosen what to extract? Try
polygons first, if there are none try lines, if there are none
take points? <br>
<br>
One possibility would be to pass the expected shapetype (Point /
Line / Polygon) to the function and take the best candidate (e.g.
longest line, largest polygon area).<br>
<br>
>How much effort (in time) do you think is required to
implement this fix?<br>
<br>
Difficult to estimate. It seems straightforward to implement the
extraction function. Then it needs to be called by the f-tools
internally and be tested with a few examples. If unit tests are
required (as mentioned by Alessandro), this seems to be the most
time consuming task to me.<br>
<br>
Regards,<br>
Marco<br>
<br>
On 24.11.2015 10:42, Matthias Kuhn wrote:<br>
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<blockquote cite="mid:565430F2.70305@opengis.ch" type="cite">
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Hi Marco<br>
<br>
Good to have your feedback, you probably know the problem best.<br>
<br>
<div class="moz-cite-prefix">On 11/24/2015 09:28 AM, Marco
Hugentobler wrote:<br>
</div>
<blockquote cite="mid:56541FA7.8070707@sourcepole.ch" type="cite">
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<div class="moz-cite-prefix">Hi<br>
<br>
>ad issue 1: update fTools to warn users when some features
cause problems<br>
>ad issue 2: quick fix fTools to convert geometry
collections to single geometry types<br>
<br>
A function that takes a geometry type and extracts the longest
line / the largest polygon / the first point from the geometry
collection should be straightforward to do.<br>
</div>
</blockquote>
<br>
Is there no requirement for multi types?<br>
Based on what indicator should be chosen what to extract? Try
polygons first, if there are none try lines, if there are none
take points?<br>
<br>
<blockquote cite="mid:56541FA7.8070707@sourcepole.ch" type="cite">
<div class="moz-cite-prefix"> <br>
>These fixes/updates would be made available as fTools
updates via the plugin installer asap<br>
<br>
If the fix does not take too long, we probably don't need a
warning at all.<br>
</div>
</blockquote>
<br>
How much effort (in time) do you think is required to implement
this fix?<br>
<br>
Regards,<br>
Matthias<br>
<br>
<blockquote cite="mid:56541FA7.8070707@sourcepole.ch" type="cite">
<div class="moz-cite-prefix"> <br>
Regards,<br>
Marco<br>
<br>
On 23.11.2015 21:35, Anita Graser wrote:<br>
</div>
<blockquote
cite="mid:CAFFV8FgYvYzu+eDGjiA90UtfkryMUHjs_dd9_soS4osRp2m5Ew@mail.gmail.com"
type="cite">
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<div class="gmail_default">Hi,</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">If you are following the psc
list, you've probably seen the thread discussing current
shortcomings of ftools (<a moz-do-not-send="true"
href="http://lists.osgeo.org/pipermail/qgis-psc/2015-November/003623.html">http://lists.osgeo.org/pipermail/qgis-psc/2015-November/003623.html</a>)</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">In short, the key issues are:</div>
<div class="gmail_default">1. When ftools encounter issues
with certain features, warning messages get written to the
log but this is largely hidden from users since they would
actively have to actively monitor the log. The problematic
features are then missing from the results but this is not
always obvious. </div>
<div class="gmail_default">2. The above issue is more common
now (since 2.10) since underlying libraries more often
(and correctly so) produce geometry collections as
outputs. These geometry collections are not handled well
by the current ftools code which is much older.</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">To address these issues, the
following suggestions have been made so far: <br>
ad issue 1: update fTools to warn users when some features
cause problems<br>
ad issue 2: quick fix fTools to convert geometry
collections to single geometry types</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">For the warnings, there's already
a first PR draft <a moz-do-not-send="true"
href="https://github.com/qgis/QGIS/pull/2432">https://github.com/qgis/QGIS/pull/2432</a>
which needs to be fleshed out. </div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">These fixes/updates would be made
available as fTools updates via the plugin installer
asap. </div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">If you have ideas how to handle
this efficiently or have already implemented code that
addresses similar issues, let us know. </div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">It would be good to have a quick
discussion in order to be able to provide improvements
fast.<br>
</div>
<div class="gmail_default"><br>
</div>
<div class="gmail_default">Best wishes,</div>
<div class="gmail_default">Anita</div>
</div>
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<pre class="moz-signature" cols="72">--
Dr. Marco Hugentobler
Sourcepole - Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:marco.hugentobler@sourcepole.ch">marco.hugentobler@sourcepole.ch</a> <a moz-do-not-send="true" class="moz-txt-link-freetext" href="http://www.sourcepole.ch">http://www.sourcepole.ch</a>
Technical Advisor QGIS Project Steering Committee </pre>
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<pre class="moz-signature" cols="72">--
Matthias Kuhn
OPENGIS.ch - <a moz-do-not-send="true" class="moz-txt-link-freetext" href="https://www.opengis.ch">https://www.opengis.ch</a>
Spatial • (Q)GIS • PostGIS • Open Source</pre>
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<pre class="moz-signature" cols="72">--
Dr. Marco Hugentobler
Sourcepole - Linux & Open Source Solutions
Weberstrasse 5, CH-8004 Zürich, Switzerland
<a class="moz-txt-link-abbreviated" href="mailto:marco.hugentobler@sourcepole.ch">marco.hugentobler@sourcepole.ch</a> <a class="moz-txt-link-freetext" href="http://www.sourcepole.ch">http://www.sourcepole.ch</a>
Technical Advisor QGIS Project Steering Committee </pre>
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