def create_layer(vector):
"""Create empty layer.
The CRS and Geometry Type of new layer are the same as of vector layer.
Attributes of the layer are copied from vector.
:param vector: Vector layer
:type vector: QgsVectorLayer
:returns: Empty vector layer (stored in memory)
:rtype: QgsVectorLayer
"""
crs = vector.crs().toWkt()
if vector.geometryType() == 0:
msg = "Points cant' be split"
raise WrongDataTypeException(msg)
elif vector.geometryType() == 1:
uri = 'LineString?crs=' + crs
elif vector.geometryType() == 2:
uri = 'Polygon?crs=' + crs
else:
msg = "Received unexpected type of layer geometry: %s" \
% (vector.geometryType(),)
raise WrongDataTypeException(msg)
result_layer = QgsVectorLayer(uri, 'intersected', 'memory')
result_provider = result_layer.dataProvider()
result_layer.startEditing()
# Copy fields from vector
vector_provider = vector.dataProvider()
fields = vector_provider.fields()
result_provider.addAttributes(fields.toList())
result_layer.commitChanges()
return result_layer
def split_by_polygon(vector,
polygon,
request=QgsFeatureRequest(),
mark_value=None):
"""Split objects from vector layer by polygon.
If request is specified, filter the objects before splitting.
If part of vector object lies in the polygon, mark it by mark_value (
optional).
:param vector: Vector layer
:type vector: QgsVectorLayer
:param polygon: Splitting polygon
:type polygon: QgsGeometry
:param request: Filter for vector objects
:type request: QgsFeatureRequest
:param mark_value: Field value to mark the objects.
:type mark_value: (field_name, field_value).or None
:returns: Vector layer with split geometry
:rtype: QgsVectorLayer
"""
def _set_feature(geometry, feature_attributes):
"""
Helper to create and set up feature
"""
included_feature = QgsFeature()
included_feature.setGeometry(geometry)
included_feature.setAttributes(feature_attributes)
return included_feature
def _update_attr_list(attributes, index, value, add_attribute=False):
"""
Helper for update list of attributes.
"""
new_attributes = attributes[:]
if add_attribute:
new_attributes.append(value)
else:
new_attributes[index] = value
return new_attributes
# Create layer to store the splitted objects
result_layer = create_layer(vector)
result_provider = result_layer.dataProvider()
fields = result_provider.fields()
# If target_field does not exist, add it:
new_field_added = False
if mark_value is not None:
target_field = mark_value[0]
if fields.indexFromName(target_field) == -1:
result_layer.startEditing()
result_provider.addAttributes(
[QgsField(target_field, QVariant.Int)])
new_field_added = True
result_layer.commitChanges()
target_value = None
if mark_value is not None:
target_field = mark_value[0]
target_value = mark_value[1]
target_field_index = result_provider.fieldNameIndex(target_field)
if target_field_index == -1:
raise WrongDataTypeException('Field not found for %s' %
target_field)
# Start split procedure
result_layer.startEditing()
for initial_feature in vector.getFeatures(request):
initial_geom = initial_feature.geometry()
attributes = initial_feature.attributes()
geometry_type = initial_geom.type()
if polygon.intersects(initial_geom):
# Find parts of initial_geom, intersecting
# with the polygon, then mark them if needed
intersection = QgsGeometry(
initial_geom.intersection(polygon)).asGeometryCollection()
for g in intersection:
if g.type() == geometry_type:
if mark_value is not None:
new_attributes = _update_attr_list(
attributes,
target_field_index,
target_value,
add_attribute=new_field_added)
else:
new_attributes = attributes
feature = _set_feature(g, new_attributes)
_ = result_layer.dataProvider().addFeatures([feature])
# Find parts of the initial_geom that do not lie in the polygon
diff_geom = QgsGeometry(
initial_geom.symDifference(polygon)).asGeometryCollection()
for g in diff_geom:
if g.type() == geometry_type:
if mark_value is not None:
new_attributes = _update_attr_list(
attributes,
target_field_index,
0,
add_attribute=new_field_added)
else:
new_attributes = attributes
feature = _set_feature(g, new_attributes)
_ = result_layer.dataProvider().addFeatures([feature])
else:
if mark_value is not None:
new_attributes = _update_attr_list(
attributes,
target_field_index,
0,
add_attribute=new_field_added)
else:
new_attributes = attributes
feature = _set_feature(initial_geom, new_attributes)
_ = result_layer.dataProvider().addFeatures([feature])
result_layer.commitChanges()
result_layer.updateExtents()
return result_layer
def split_by_polygon2(
vector,
polygon_layer,
request=QgsFeatureRequest(),
use_contains_operation=False,
mark_value=None):
"""Split objects from vector layer by polygon.
If request is specified, filter the objects before splitting.
If part of vector object lies in the polygon, mark it by mark_value (
optional).
:param vector: Vector layer
:type vector: QgsVectorLayer
:param polygon_layer: Splitting polygons layer
:type polygon_layer: QgsVectorLayer
:param request: Filter for vector objects
:type request: QgsFeatureRequest
:param use_contains_operation: Whether to use geometrical containment.
:type use_contains_operation: bool
:param mark_value: Field value to mark the objects.
:type mark_value: (field_name, field_value).or None
:returns: Vector layer with split geometry
:rtype: QgsVectorLayer
"""
def _set_feature(geometry, attributes):
"""
Helper to create and set up feature
"""
included_feature = QgsFeature()
included_feature.setGeometry(geometry)
included_feature.setAttributes(attributes)
return included_feature
def _update_attr_list(attributes, index, value, add_attribute=False):
"""
Helper for update list of attributes.
"""
new_attributes = attributes[:]
if add_attribute:
new_attributes.append(value)
else:
new_attributes[index] = value
return new_attributes
# Create layer to store the split objects
result_layer = create_layer(vector)
result_provider = result_layer.dataProvider()
fields = result_provider.fields()
# If target_field does not exist, add it:
new_field_added = False
if mark_value is not None:
target_field = mark_value[0]
if fields.indexFromName(target_field) == -1:
result_layer.startEditing()
result_provider.addAttributes(
[QgsField(target_field, QVariant.Int)])
new_field_added = True
result_layer.commitChanges()
target_value = None
if mark_value is not None:
target_field = mark_value[0]
target_value = mark_value[1]
target_field_index = result_provider.fieldNameIndex(target_field)
if target_field_index == -1:
raise WrongDataTypeException(
'Field not found for %s' % target_field)
# Start split procedure
line_geoms = []
line_attributes = []
for initial_feature in vector.getFeatures(request):
initial_geom = initial_feature.geometry()
line_geoms.append(QgsGeometry(initial_geom))
attributes = initial_feature.attributes()
line_attributes.append(attributes)
geometry_type = initial_geom.type()
poly_geoms = []
for polygon_feature in polygon_layer.getFeatures(request):
# Using simplify 1 should remove any pseudonodes on the polygon
# and speed up polygon operations. TS
# polygon = polygon_feature.geometry().simplify(1)
# disabled for now (see #1300 Y.A.)
polygon = polygon_feature.geometry()
poly_geoms.append(QgsGeometry(polygon))
result_layer.startEditing()
for polygon in poly_geoms:
for initial_geom, attributes in \
itertools.izip(line_geoms, line_attributes):
if use_contains_operation:
poly_contains = polygon.contains(initial_geom)
else:
poly_contains = False
poly_intersect = False
if not poly_contains:
poly_intersect = polygon.intersects(initial_geom)
if poly_contains or poly_intersect:
# Find parts of initial_geom, intersecting
# with the polygon, then mark them if needed
if poly_contains:
g = initial_geom
if mark_value is not None:
new_attributes = _update_attr_list(
attributes,
target_field_index,
target_value,
add_attribute=new_field_added
)
else:
new_attributes = attributes
feature = _set_feature(g, new_attributes)
_ = result_layer.dataProvider().addFeatures([feature])
else:
intersection = QgsGeometry(
initial_geom.intersection(polygon)
).asGeometryCollection()
for g in intersection:
if g.type() == geometry_type:
if mark_value is not None:
new_attributes = _update_attr_list(
attributes,
target_field_index,
target_value,
add_attribute=new_field_added
)
else:
new_attributes = attributes
feature = _set_feature(g, new_attributes)
_ = result_layer.dataProvider().\
addFeatures([feature])
result_layer.commitChanges()
result_layer.updateExtents()
return result_layer