[processing] [feature] split lines with lines

Author: Bernhard Ströbl

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

@@ -118,6 +118,7 @@
 from SetRasterStyle import SetRasterStyle
 from SelectByExpression import SelectByExpression
 from HypsometricCurves import HypsometricCurves
+from SplitLinesWithLines import SplitLinesWithLines
 # from VectorLayerHistogram import VectorLayerHistogram
 # from VectorLayerScatterplot import VectorLayerScatterplot
 # from MeanAndStdDevPlot import MeanAndStdDevPlot
@@ -169,6 +170,7 @@ def __init__(self):
                         PostGISExecuteSQL(), ImportIntoPostGIS(),
                         SetVectorStyle(), SetRasterStyle(),
                         SelectByExpression(), HypsometricCurves(),
+                        SplitLinesWithLines()
                         # ------ raster ------
                         # CreateConstantRaster(),
                         # ------ graphics ------

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

@@ -0,0 +1,140 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    SplitLines.py
+    ---------------------
+    Date                 : November 2014
+    Copyright            : (C) 2014 by Bernhard Ströbl
+    Email                : bernhard dot stroebl at jena dot de
+***************************************************************************
+*                                                                         *
+*   This program is free software; you can redistribute it and/or modify  *
+*   it under the terms of the GNU General Public License as published by  *
+*   the Free Software Foundation; either version 2 of the License, or     *
+*   (at your option) any later version.                                   *
+*                                                                         *
+***************************************************************************
+"""
+
+__author__ = 'Bernhard Ströbl'
+__date__ = 'November 2014'
+__copyright__ = '(C) 2014, Bernhard Ströbl'
+
+# This will get replaced with a git SHA1 when you do a git archive
+
+__revision__ = '$Format:%H$'
+
+from PyQt4.QtCore import *
+from PyQt4.QtGui import *
+from qgis.core import *
+from processing.core.GeoAlgorithm import GeoAlgorithm
+from processing.core.parameters import ParameterVector
+from processing.core.outputs import OutputVector
+from processing.tools import dataobjects
+from processing.tools import vector
+
+
+class SplitLinesWithLines(GeoAlgorithm):
+
+    INPUT_A = 'INPUT_A'
+    INPUT_B = 'INPUT_B'
+
+    OUTPUT = 'OUTPUT'
+
+    def defineCharacteristics(self):
+        self.name = 'Split lines with lines'
+        self.group = 'Vector overlay tools'
+        self.addParameter(ParameterVector(self.INPUT_A, 'Input layer',
+                          [ParameterVector.VECTOR_TYPE_LINE]))
+        self.addParameter(ParameterVector(self.INPUT_B, 'Split layer',
+                          [ParameterVector.VECTOR_TYPE_LINE]))
+
+        self.addOutput(OutputVector(self.OUTPUT, 'Split lines'))
+
+    def processAlgorithm(self, progress):
+        layerA = dataobjects.getObjectFromUri(
+                self.getParameterValue(self.INPUT_A))
+        layerB = dataobjects.getObjectFromUri(
+                self.getParameterValue(self.INPUT_B))
+
+        fieldList = layerA.pendingFields()
+
+        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fieldList,
+                QGis.WKBLineString, layerA.dataProvider().crs())
+
+        spatialIndex = vector.spatialindex(layerB)
+
+        inFeatA = QgsFeature()
+        inFeatB = QgsFeature()
+        outFeat = QgsFeature()
+        inGeom = QgsGeometry()
+        splitGeom = QgsGeometry()
+
+        features = vector.features(layerA)
+        current = 0
+        total = 100.0 / float(len(features))
+
+        for inFeatA in features:
+            inGeom = inFeatA.geometry()
+            attrsA = inFeatA.attributes()
+            outFeat.setAttributes(attrsA)
+            inLines = [inGeom]
+            lines = spatialIndex.intersects(inGeom.boundingBox())
+
+            if len(lines) > 0: #hasIntersections
+                splittingLines = []
+
+                for i in lines:
+                    request = QgsFeatureRequest().setFilterFid(i)
+                    inFeatB = layerB.getFeatures(request).next()
+                    splitGeom = QgsGeometry(inFeatB.geometry())
+
+                    if inGeom.intersects(splitGeom):
+                        splittingLines.append(splitGeom)
+
+                if len(splittingLines) > 0:
+                    for splitGeom in splittingLines:
+                        splitterPList = vector.extractPoints(splitGeom)
+                        outLines = []
+
+                        while len(inLines) > 0:
+                            inGeom = inLines.pop()
+                            inPoints = vector.extractPoints(inGeom)
+
+                            if inGeom.intersects(splitGeom):
+                                try:
+                                    result, newGeometries, topoTestPoints = inGeom.splitGeometry(splitterPList, False)
+                                except:
+                                    QgsMessageLog.logMessage("exception")
+                                    result = 1
+
+                                # splitGeometry: If there are several intersections
+                                # between geometry and splitLine, only the first one is considered.
+                                if result == 0: #split occured
+
+                                    if inPoints == vector.extractPoints(inGeom):
+                                        # bug in splitGeometry: sometimes it returns 0 but
+                                        # the geometry is unchanged
+                                        outLines.append(inGeom)
+                                    else:
+                                        inLines.append(inGeom)
+
+                                        for aNewGeom in newGeometries:
+                                           inLines.append(aNewGeom)
+                                else:
+                                    outLines.append(inGeom)
+                            else:
+                                outLines.append(inGeom)
+
+                        inLines = outLines
+
+
+            for aLine in inLines:
+                outFeat.setGeometry(aLine)
+                writer.addFeature(outFeat)
+
+            current += 1
+            progress.setPercentage(int(current * total))
+
+        del writer

python/plugins/processing/algs/qgis/help/splitlineswithlines.rst

@@ -0,0 +1,29 @@
+SPLIT LINES WITH LINES
+=======================
+
+Description
+-----------
+This algorithm splits the features of a line layer with the lines of another line layer. 
+
+Parameters
+----------
+
+- ``Input layer[Vector]``:line layer
+- ``Split layer[Vector]``:line layer
+
+Outputs
+-------
+
+- ``Output layer[Vector]``: resulting layer
+
+See also
+---------
+
+
+Console usage
+-------------
+
+
+::
+
+	processing.runalg('qgis:splitlineswithlines', input_lines, split_lines, output)