Class: QgsGeometryCollection

Geometry collection

Class Hierarchy

Base classes

QgsAbstractGeometry

Abstract base class for all geometries

Subclasses

QgsMultiCurve	Multi curve geometry collection.
QgsMultiPoint	Multi point geometry collection.
QgsMultiSurface	Multi surface geometry collection.

Methods

addGeometries	Adds a list of geometries to the collection, transferring ownership to the collection.
addGeometry	Adds a geometry and takes ownership.
extractPartsByType	Returns a new QgsGeometryCollection subclass which consists of the parts of this collection which match the specified WKB type.
fromCollectionWkt	Reads a collection from a WKT string.
geometryN	Returns a geometry from within the collection.
insertGeometry	Inserts a geometry before a specified index and takes ownership.
numGeometries	Returns the number of geometries within the collection.
removeGeometry	Removes a geometry from the collection by index.
reserve	Attempts to allocate memory for at least size geometries.
segmentize	Returns a geometry without curves.
takeGeometries	Removes all geometries from the collection, returning them and their ownership to the caller.
wktOmitChildType	Returns whether child type names are omitted from Wkt representations of the collection

class qgis.core.QgsGeometryCollection

Bases: QgsAbstractGeometry

__init__()

Constructor for an empty geometry collection.

__init__(c: QgsGeometryCollection)

Parameters:

c (QgsGeometryCollection)

addGeometries(self, geometries: Iterable[QgsAbstractGeometry]) → bool

Adds a list of geometries to the collection, transferring ownership to the collection.

Returns True in case of success.

Added in version 3.38.

Parameters:

geometries (Iterable[QgsAbstractGeometry])

Return type:

bool

addGeometry(self, g: QgsAbstractGeometry | None) → bool

Adds a geometry and takes ownership. Returns True in case of success.

Parameters:

g (Optional[QgsAbstractGeometry])

Return type:

bool

extractPartsByType(self, type: Qgis.WkbType, useFlatType: bool = True) → QgsGeometryCollection | None

Returns a new QgsGeometryCollection subclass which consists of the parts of this collection which match the specified WKB type.

For instance, if type is Qgis.WkbType.Polygon, then the returned object will be a QgsMultiPolygon object containing just the polygons from this collection.

If useFlatType is True, then the WKB types of component geometries from this collection will be flattened prior to comparing with type. (I.e. the presence of Z / M dimensions will be ignored when comparing against type).

Added in version 3.36.

Parameters:

• type (Qgis.WkbType)

• useFlatType (bool = True)

Return type:

Optional[QgsGeometryCollection]

fromCollectionWkt(self, wkt: str | None, subtypes: Iterable[QgsAbstractGeometry], defaultChildWkbType: str | None = '') → bool

Reads a collection from a WKT string.

Parameters:

• wkt (Optional[str])

• subtypes (Iterable[QgsAbstractGeometry])

• defaultChildWkbType (Optional[str] = '')

Return type:

bool

geometryN(self, n: int) → QgsAbstractGeometry

Returns a geometry from within the collection.

Parameters:

n (int) – index of geometry to return.

Raises:

IndexError – if no geometry with the specified index exists.

Return type:

QgsAbstractGeometry

insertGeometry(self, g: QgsAbstractGeometry | None, index: int) → bool

Inserts a geometry before a specified index and takes ownership. Returns True in case of success.

Parameters:

• g (Optional[QgsAbstractGeometry]) – geometry to insert. Ownership is transferred to the collection.

• index (int) – position to insert geometry before

Return type:

bool

numGeometries(self) → int

Returns the number of geometries within the collection.

Return type:

int

removeGeometry(self, nr: int) → bool

Removes a geometry from the collection by index.

Return type:

bool

Returns:

True if removal was successful.

Raises:

IndexError – if no geometry with the specified index exists.

Parameters:

nr (int)

reserve(self, size: int)

Attempts to allocate memory for at least size geometries.

If the number of geometries is known in advance, calling this function prior to adding geometries will prevent reallocations and memory fragmentation.

Added in version 3.10.

Parameters:

size (int)

segmentize(self, tolerance: float = M_PI_2 / 90, toleranceType: QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) → QgsAbstractGeometry | None

Returns a geometry without curves. Caller takes ownership

Parameters:

• tolerance (float = M_PI_2/90) – segmentation tolerance

• toleranceType (QgsAbstractGeometry.SegmentationToleranceType = QgsAbstractGeometry.MaximumAngle) – maximum segmentation angle or maximum difference between approximation and curve

Return type:

Optional[QgsAbstractGeometry]

takeGeometries(self) → List[QgsAbstractGeometry]

Removes all geometries from the collection, returning them and their ownership to the caller.

Added in version 3.38.

Return type:

List[QgsAbstractGeometry]

wktOmitChildType(self) → bool

Returns whether child type names are omitted from Wkt representations of the collection

Return type:

bool