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[FEATURE][processing] Topological coloring can have a minimum
distance between features assigned the same color set
1 parent 5c43e0b commit 74abd5b

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5 files changed

+206
-4
lines changed

5 files changed

+206
-4
lines changed

‎python/plugins/processing/algs/help/qgis.yaml

+2
Original file line numberDiff line numberDiff line change
@@ -547,6 +547,8 @@ qgis:texttofloat: >
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qgis:topologicalcoloring: >
548548
This algorithm assigns a color index to polygon features in such a way that no adjacent polygons share the same color index, whilst minimizing the number of colors required.
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550+
An optional minimum distance between features assigned the same color can be set to prevent nearby (but non-touching) features from being assigned equal colors.
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The algorithm allows choice of method to use when assigning colors. The default method attempts to assign colors so that the count of features assigned to each individual color index is balanced.
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The 'by assigned area' mode instead assigns colors so that the total area of features assigned to each color is balanced. This mode can be useful to help avoid large features resulting in one of the colors appearing more dominant on a colored map.

‎python/plugins/processing/algs/qgis/TopoColors.py

+12-4
Original file line numberDiff line numberDiff line change
@@ -52,6 +52,7 @@
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class TopoColor(GeoAlgorithm):
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INPUT_LAYER = 'INPUT_LAYER'
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MIN_COLORS = 'MIN_COLORS'
55+
MIN_DISTANCE = 'MIN_DISTANCE'
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BALANCE = 'BALANCE'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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@@ -64,6 +65,8 @@ def defineCharacteristics(self):
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self.tr('Input layer'), [dataobjects.TYPE_VECTOR_POLYGON]))
6566
self.addParameter(ParameterNumber(self.MIN_COLORS,
6667
self.tr('Minimum number of colors'), 1, 1000, 4))
68+
self.addParameter(ParameterNumber(self.MIN_DISTANCE,
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self.tr('Minimum distance between features'), 0.0, 999999999.0, 0.0))
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balance_by = [self.tr('By feature count'),
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self.tr('By assigned area'),
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self.tr('By distance between colors')]
@@ -79,6 +82,7 @@ def processAlgorithm(self, feedback):
7982
self.getParameterValue(self.INPUT_LAYER))
8083
min_colors = self.getParameterValue(self.MIN_COLORS)
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balance_by = self.getParameterValue(self.BALANCE)
85+
min_distance = self.getParameterValue(self.MIN_DISTANCE)
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8387
fields = layer.fields()
8488
fields.append(QgsField('color_id', QVariant.Int))
@@ -91,7 +95,7 @@ def processAlgorithm(self, feedback):
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9296
features = {f.id(): f for f in vector.features(layer)}
9397

94-
topology, id_graph = self.compute_graph(features, feedback)
98+
topology, id_graph = self.compute_graph(features, feedback, min_distance=min_distance)
9599
feature_colors = ColoringAlgorithm.balanced(features,
96100
balance=balance_by,
97101
graph=topology,
@@ -119,7 +123,7 @@ def processAlgorithm(self, feedback):
119123
del writer
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121125
@staticmethod
122-
def compute_graph(features, feedback, create_id_graph=False):
126+
def compute_graph(features, feedback, create_id_graph=False, min_distance=0):
123127
""" compute topology from a layer/field """
124128
s = Graph(sort_graph=False)
125129
id_graph = None
@@ -134,10 +138,14 @@ def compute_graph(features, feedback, create_id_graph=False):
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135139
i = 0
136140
for feature_id, f in features_with_geometry.items():
137-
engine = QgsGeometry.createGeometryEngine(f.geometry().geometry())
141+
g = f.geometry()
142+
if min_distance > 0:
143+
g = g.buffer(min_distance, 5)
144+
145+
engine = QgsGeometry.createGeometryEngine(g.geometry())
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engine.prepareGeometry()
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140-
feature_bounds = f.geometry().boundingBox()
148+
feature_bounds = g.boundingBox()
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# grow bounds a little so we get touching features
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feature_bounds.grow(feature_bounds.width() * 0.01)
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intersections = index.intersects(feature_bounds)

‎python/plugins/processing/tests/testdata/expected/topocolor_polys_min_dist.gfs

+46
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
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<GMLFeatureClassList>
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<GMLFeatureClass>
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<Name>topocolor_polys_min_dist</Name>
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<ElementPath>topocolor_polys_min_dist</ElementPath>
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<!--POLYGON-->
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<GeometryType>3</GeometryType>
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<SRSName>EPSG:4326</SRSName>
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<DatasetSpecificInfo>
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<FeatureCount>11</FeatureCount>
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<ExtentXMin>-0.76065</ExtentXMin>
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<ExtentXMax>14.23935</ExtentXMax>
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<ExtentYMin>-6.11331</ExtentYMin>
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<ExtentYMax>5.88669</ExtentYMax>
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</DatasetSpecificInfo>
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<PropertyDefn>
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<Name>left</Name>
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<ElementPath>left</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>top</Name>
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<ElementPath>top</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>right</Name>
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<ElementPath>right</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
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<Name>bottom</Name>
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<ElementPath>bottom</ElementPath>
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<Type>Real</Type>
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</PropertyDefn>
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<PropertyDefn>
36+
<Name>id</Name>
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<ElementPath>id</ElementPath>
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<Type>Integer</Type>
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</PropertyDefn>
40+
<PropertyDefn>
41+
<Name>color_id</Name>
42+
<ElementPath>color_id</ElementPath>
43+
<Type>Integer</Type>
44+
</PropertyDefn>
45+
</GMLFeatureClass>
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</GMLFeatureClassList>

‎python/plugins/processing/tests/testdata/expected/topocolor_polys_min_dist.gml

+133
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,133 @@
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<?xml version="1.0" encoding="utf-8" ?>
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<ogr:FeatureCollection
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation=""
5+
xmlns:ogr="http://ogr.maptools.org/"
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xmlns:gml="http://www.opengis.net/gml">
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<gml:boundedBy>
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<gml:Box>
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<gml:coord><gml:X>-0.760650357995228</gml:X><gml:Y>-6.11330548926014</gml:Y></gml:coord>
10+
<gml:coord><gml:X>14.2393496420048</gml:X><gml:Y>5.88669451073986</gml:Y></gml:coord>
11+
</gml:Box>
12+
</gml:boundedBy>
13+
14+
<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.0">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-0.760650357995228,-0.113305489260142 2.23934964200477,-0.113305489260142 2.23934964200477,-3.11330548926014 -0.760650357995228,-3.11330548926014 -0.760650357995228,-0.113305489260142</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:left>-0.76065</ogr:left>
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<ogr:top>-0.11331</ogr:top>
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<ogr:right>2.23935</ogr:right>
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<ogr:bottom>-3.11331</ogr:bottom>
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<ogr:id>3</ogr:id>
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<ogr:color_id>7</ogr:color_id>
23+
</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
25+
<gml:featureMember>
26+
<ogr:topocolor_polys_min_dist fid="adjacent_polys.1">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>-0.760650357995228,-3.11330548926014 2.23934964200477,-3.11330548926014 2.23934964200477,-6.11330548926014 -0.760650357995228,-6.11330548926014 -0.760650357995228,-3.11330548926014</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:left>-0.76065</ogr:left>
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<ogr:top>-3.11331</ogr:top>
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<ogr:right>2.23935</ogr:right>
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<ogr:bottom>-6.11331</ogr:bottom>
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<ogr:id>4</ogr:id>
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<ogr:color_id>2</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
37+
<ogr:topocolor_polys_min_dist fid="adjacent_polys.2">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5.23934964200477,-0.113305489260142 8.23934964200477,-0.113305489260142 8.23934964200477,-3.11330548926014 5.23934964200477,-3.11330548926014 5.23934964200477,-0.113305489260142</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:left>5.23935</ogr:left>
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<ogr:top>-0.11331</ogr:top>
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<ogr:right>8.23935</ogr:right>
42+
<ogr:bottom>-3.11331</ogr:bottom>
43+
<ogr:id>11</ogr:id>
44+
<ogr:color_id>1</ogr:color_id>
45+
</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
47+
<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.3">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5.23934964200477,-3.11330548926014 8.23934964200477,-3.11330548926014 8.23934964200477,-6.11330548926014 5.23934964200477,-6.11330548926014 5.23934964200477,-3.11330548926014</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
50+
<ogr:left>5.23935</ogr:left>
51+
<ogr:top>-3.11331</ogr:top>
52+
<ogr:right>8.23935</ogr:right>
53+
<ogr:bottom>-6.11331</ogr:bottom>
54+
<ogr:id>12</ogr:id>
55+
<ogr:color_id>3</ogr:color_id>
56+
</ogr:topocolor_polys_min_dist>
57+
</gml:featureMember>
58+
<gml:featureMember>
59+
<ogr:topocolor_polys_min_dist fid="adjacent_polys.4">
60+
<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>8.23934964200477,-3.11330548926014 11.2393496420048,-3.11330548926014 11.2393496420048,-6.11330548926014 8.23934964200477,-6.11330548926014 8.23934964200477,-3.11330548926014</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
61+
<ogr:left>8.23935</ogr:left>
62+
<ogr:top>-3.11331</ogr:top>
63+
<ogr:right>11.23935</ogr:right>
64+
<ogr:bottom>-6.11331</ogr:bottom>
65+
<ogr:id>16</ogr:id>
66+
<ogr:color_id>5</ogr:color_id>
67+
</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
69+
<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.5">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>11.2393496420048,-0.113305489260142 14.2393496420048,-0.113305489260142 14.2393496420048,-3.11330548926014 11.2393496420048,-3.11330548926014 11.2393496420048,-0.113305489260142</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
72+
<ogr:left>11.23935</ogr:left>
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<ogr:top>-0.11331</ogr:top>
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<ogr:right>14.23935</ogr:right>
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<ogr:bottom>-3.11331</ogr:bottom>
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<ogr:id>19</ogr:id>
77+
<ogr:color_id>4</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.6">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>11.2393496420048,-3.11330548926014 14.2393496420048,-3.11330548926014 14.2393496420048,-6.11330548926014 11.2393496420048,-6.11330548926014 11.2393496420048,-3.11330548926014</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
83+
<ogr:left>11.23935</ogr:left>
84+
<ogr:top>-3.11331</ogr:top>
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<ogr:right>14.23935</ogr:right>
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<ogr:bottom>-6.11331</ogr:bottom>
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<ogr:id>20</ogr:id>
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<ogr:color_id>7</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.7">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>2.23934964200477,5.88669451073986 5.23934964200477,5.88669451073986 5.23934964200477,2.88669451073986 2.23934964200477,2.88669451073986 2.23934964200477,-0.113305489260142 -0.760650357995228,-0.113305489260142 -0.760650357995228,2.88669451073986 -0.760650357995228,5.88669451073986 2.23934964200477,5.88669451073986</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
94+
<ogr:left>2.23935</ogr:left>
95+
<ogr:top>5.88669</ogr:top>
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<ogr:right>5.23935</ogr:right>
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<ogr:bottom>2.88669</ogr:bottom>
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<ogr:id>5</ogr:id>
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<ogr:color_id>3</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.8">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5.23934964200477,2.88669451073986 8.23934964200477,2.88669451073986 11.2393496420048,2.88669451073986 11.2393496420048,-0.113305489260142 11.2393496420048,-3.11330548926014 8.23934964200477,-3.11330548926014 8.23934964200477,-0.113305489260142 5.23934964200477,-0.113305489260142 5.23934964200477,2.88669451073986</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:left>5.23935</ogr:left>
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<ogr:top>2.88669</ogr:top>
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<ogr:right>8.23935</ogr:right>
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<ogr:id>10</ogr:id>
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<ogr:color_id>2</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.9">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>2.23934964200477,2.88669451073986 5.23934964200477,2.88669451073986 5.23934964200477,-0.113305489260142 5.23934964200477,-3.11330548926014 5.23934964200477,-6.11330548926014 2.23934964200477,-6.11330548926014 2.23934964200477,-3.11330548926014 2.23934964200477,-0.113305489260142 2.23934964200477,2.88669451073986</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
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<ogr:left>2.23935</ogr:left>
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<ogr:top>2.88669</ogr:top>
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<ogr:right>5.23935</ogr:right>
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<ogr:id>6</ogr:id>
119+
<ogr:color_id>4</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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<gml:featureMember>
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<ogr:topocolor_polys_min_dist fid="adjacent_polys.10">
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<ogr:geometryProperty><gml:Polygon srsName="EPSG:4326"><gml:outerBoundaryIs><gml:LinearRing><gml:coordinates>5.23934964200477,5.88669451073986 8.23934964200477,5.88669451073986 11.2393496420048,5.88669451073986 14.2393496420048,5.88669451073986 14.2393496420048,2.88669451073986 14.2393496420048,-0.113305489260142 11.2393496420048,-0.113305489260142 11.2393496420048,2.88669451073986 8.23934964200477,2.88669451073986 5.23934964200477,2.88669451073986 5.23934964200477,5.88669451073986</gml:coordinates></gml:LinearRing></gml:outerBoundaryIs></gml:Polygon></ogr:geometryProperty>
125+
<ogr:left>5.23935</ogr:left>
126+
<ogr:top>5.88669</ogr:top>
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<ogr:right>8.23935</ogr:right>
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<ogr:bottom>2.88669</ogr:bottom>
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<ogr:id>9</ogr:id>
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<ogr:color_id>6</ogr:color_id>
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</ogr:topocolor_polys_min_dist>
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</gml:featureMember>
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</ogr:FeatureCollection>

‎python/plugins/processing/tests/testdata/qgis_algorithm_tests.yaml

+13
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@@ -2385,3 +2385,16 @@ tests:
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name: expected/topocolor_polys.gml
23862386
type: vector
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2388+
- algorithm: qgis:topologicalcoloring
2389+
name: Topological coloring w/ min distance
2390+
params:
2391+
BALANCE: '0'
2392+
INPUT_LAYER:
2393+
name: custom/adjacent_polys.gml
2394+
type: vector
2395+
MIN_COLORS: 4
2396+
MIN_DISTANCE: 4.0
2397+
results:
2398+
OUTPUT_LAYER:
2399+
name: expected/topocolor_polys_min_dist.gml
2400+
type: vector

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