def run(self):
layer = self.iface.mapCanvas().currentLayer()
if layer is None:
QMessageBox.information(None, "Chinese Postman",
"Please select a layer.")
return
features = layer.selectedFeatures()
if len(features) == 0:
QMessageBox.information(
None, "Chinese Postman",
"Please select an area. The 'Select Features by Polygon' tool "
+ "works well for this.")
return
graph = build_graph(features)
components = postman.graph_components(graph)
if len(components) > 1:
QMessageBox.information(
None, "Chinese Postman",
"Warning: the selected area contains multiple disconnected " +
"components - only the largest one will be used.")
if len(components) == 0:
QMessageBox.information(
None, "Chinese Postman",
"Error: Could not find any components. Try selecting different features."
)
return
component = components[0]
eulerian_graph, nodes = postman.single_chinese_postman_path(component)
in_length = postman.edge_sum(component) / 1000.0
path_length = postman.edge_sum(eulerian_graph) / 1000.0
duplicate_length = path_length - in_length
newlayer = build_layer(eulerian_graph, nodes, layer.crs())
symbol = build_symbol(newlayer)
newlayer.setRendererV2(QgsSingleSymbolRendererV2(symbol))
QgsMapLayerRegistry.instance().addMapLayer(newlayer)
info = ""
info += "Total length of roads: %.3f km\n" % in_length
info += "Total length of path: %.3f km\n" % path_length
info += "Length of sections visited twice: %.3f km\n" % duplicate_length
info += "\n"
info += "(If the above values do not make sense, consider changing CRS.)\n"
QMessageBox.information(None, "Chinese Postman", info)
def test_postman(self):
"""
Test the end result.
"""
graph = postman.import_csv_graph(open('test_graph.csv', 'r'))
components = postman.graph_components(graph)
# Only use the largest component
component = components[0]
eulerian_graph, nodes = postman.single_chinese_postman_path(component)
in_length = postman.edge_sum(graph) / 1000.0
path_length = postman.edge_sum(eulerian_graph) / 1000.0
duplicate_length = path_length - in_length
self.assertAlmostEqual(in_length, 14.889)
self.assertAlmostEqual(path_length, 20.316)
self.assertAlmostEqual(duplicate_length, 5.427)
def test_postman(self):
"""
Test the end result.
"""
graph = postman.import_csv_graph(open('test_graph.csv', 'r'))
components = postman.graph_components(graph)
# Only use the largest component
component = components[0]
eulerian_graph, nodes = postman.single_chinese_postman_path(component)
in_length = postman.edge_sum(graph) / 1000.0
path_length = postman.edge_sum(eulerian_graph) / 1000.0
duplicate_length = path_length - in_length
self.assertAlmostEqual(in_length, 14.889)
self.assertAlmostEqual(path_length, 20.316)
self.assertAlmostEqual(duplicate_length, 5.427)
def run(self):
layer = self.iface.mapCanvas().currentLayer()
if layer is None:
QMessageBox.information(None, "Chinese Postman", "Please select a layer.")
return
features = layer.selectedFeatures()
if len(features) == 0:
QMessageBox.information(None, "Chinese Postman", "Please select an area. The 'Select Features by Polygon' tool " +
"works well for this.")
return
graph = build_graph(features)
components = postman.graph_components(graph)
if len(components) > 1:
QMessageBox.information(None, "Chinese Postman", "Warning: the selected area contains multiple disconnected " +
"components - only the largest one will be used.")
if len(components) == 0:
QMessageBox.information(None, "Chinese Postman", "Error: Could not find any components. Try selecting different features.")
return
component = components[0]
eulerian_graph, nodes = postman.single_chinese_postman_path(component)
in_length = postman.edge_sum(component)/1000.0
path_length = postman.edge_sum(eulerian_graph)/1000.0
duplicate_length = path_length - in_length
newlayer = build_layer(eulerian_graph, nodes, layer.crs())
symbol = build_symbol(newlayer)
newlayer.setRendererV2(QgsSingleSymbolRendererV2(symbol))
QgsMapLayerRegistry.instance().addMapLayer(newlayer)
info = ""
info += "Total length of roads: %.3f km\n" % in_length
info += "Total length of path: %.3f km\n" % path_length
info += "Length of sections visited twice: %.3f km\n" % duplicate_length
info += "\n"
info += "(If the above values do not make sense, consider changing CRS.)\n"
QMessageBox.information(None, "Chinese Postman", info)