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Hi Tim,<br>
Awesome - my first foray into python & QGIS, after wanting to
get there more than a year ago. Big thanks for the prod.<br>
I've changed your code as the layer to be updated was 'a', not 'b'.<br>
<br>
So using coordinates from the attribute columns of 'a', I need to
update an attribute column of 'a' with an attribute column of the
feature in 'b' that was selected by these coords.<br>
<br>
The script below works, BUT, it seems like an index is a bit out,
because not all the features in 'a' are updated with the correct
feature in 'b'.<br>
I haven't checked them all, but it seems like "all but 1" are
correct.<br>
The few I've checked (that are wrong) do have the correct coord
value to use for selecting a feature from 'b'.<br>
<br>
My version is as below - can you give this some thought?<br>
<br>
Thanks & keep well,<br>
Zoltan<br>
<blockquote>reg = QgsMapLayerRegistry.instance()<br>
a = reg.mapLayersByName('g21c_2000')[0]<br>
b = reg.mapLayersByName('CM19_fptn')[0]<br>
collection = {}<br>
index = QgsSpatialIndex()<br>
for f in b.getFeatures():<br>
index.insertFeature(f)<br>
collection[f.id()] = f<br>
with edit(a):<br>
for af in a.getFeatures():<br>
p = QgsPoint(af['FptnLong'], af['FptnLat'])<br>
box = QgsRectangle(p, p) <br>
for key in index.intersects(box):<br>
feature = collection[key]<br>
print feature['ID'], af['SGcode'], af['FptnLong'],
af['FptnLat']<br>
af['SGCode'] = feature['ID'] <br>
a.updateFeature(af)<br>
</blockquote>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 2016-07-07 23:38, Tim Sutton wrote:<br>
</div>
<blockquote
cite="mid:393F571A-531E-49BE-AA9A-9F39F7373A6A@kartoza.com"
type="cite">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Hi Zoltan
<div class=""><br class="">
</div>
<div class=""><br class="">
<div>
<blockquote type="cite" class="">
<div class="">On 07 Jul 2016, at 5:55 PM, Zoltan Szecsei
<<a moz-do-not-send="true"
href="mailto:zoltans@geograph.co.za" class="">zoltans@geograph.co.za</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<meta http-equiv="content-type" content="text/html;
charset=utf-8" class="">
<div bgcolor="#FFFFFF" text="#000000" class=""> Hi
Everyone,<br class="">
Maybe someone can give me a prod in the right direction?<br
class="">
<br class="">
I have two Shape files (both polygons).<br class="">
I'm trying to copy an attribute field value from B.shp
into A.shp, using Lon and Lat from two of A.shp
attribute fields to select the relevant polygon's
attribute in B.shp.<br class="">
<br class="">
In other words:<br class="">
<blockquote class="">A.shp attribute fields are:
"Name", "Longitude" and "Latitude"<br class="">
B.shp attribute field is "Name"<br class="">
</blockquote>
Using the LatLong coords in the attribute fields of
A.shp, I want to select a polygon in B.shp, and write
that polygons "Name" contents into this A.shp's "Name"
field.<br class="">
<br class="">
Is the field calculator up for this?<br class="">
</div>
</div>
</blockquote>
<div><br class="">
</div>
<div>I don't think so - its not really set up for doing
inter-layer references. I wrote a few lines of python that
will do it though (assumes you have two layers loaded with
names a and b in the layers list:</div>
<div><br class="">
</div>
<div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">reg = QgsMapLayerRegistry.instance()</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">a = reg.mapLayersByName('a')[0]</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">b = reg.mapLayersByName('b')[0]</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">collection = {}</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">index = QgsSpatialIndex()</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">for f in b.getFeatures():</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> index.insertFeature(f)</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> collection[f.id()] = f</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class="">with edit(b):</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> for af in a.getFeatures():</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> p = QgsPoint(af['lon'],
af['lat'])</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> box = QgsRectangle(p, p) </div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> for key in
index.intersects(box):</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> feature = collection[key]</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> print feature['name'],
af['name'], af['lon'], af['lat']</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> feature['name'] =
af['name']</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69);" class=""> b.updateFeature(feature)</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class="">Just paste that into
the QGIS python console and it will update the name field
of b with the value in a for the places where the
attributes lon, lat in a intersect b.</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class="">Please test in a
sandbox before trying on your production data....</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class="">Regards</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class=""><br class="">
</div>
<div style="margin: 0px; line-height: normal; color: rgb(69,
69, 69); min-height: 14px;" class="">Tim</div>
</div>
<br class="">
<blockquote type="cite" class="">
<div class="">
<div bgcolor="#FFFFFF" text="#000000" class=""> I've been
trying to find ways of reference fields in separate maps
(layers), but neither Google or I are winning at this.<br
class="">
<br class="">
Regards, and TIA,<br class="">
Zoltan<br class="">
<br class="">
<br class="">
<br class="">
<br class="">
<br class="">
<pre class="moz-signature" cols="72">--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.geograph.co.za/">www.geograph.co.za</a>
===========================================</pre>
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
===========================================</pre>
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