GEOS APILink to this heading
BackgroundLink to this heading
What is GEOS?Link to this heading
GEOS stands for Geometry Engine - Open Source, and is a C++ library, ported from the Java Topology Suite. GEOS implements the OpenGIS Simple Features for SQL spatial predicate functions and spatial operators. GEOS, now an OSGeo project, was initially developed and maintained by Refractions Research of Victoria, Canada.
FeaturesLink to this heading
GeoDjango implements a high-level Python wrapper for the GEOS library, its features include:
A BSD-licensed interface to the GEOS geometry routines, implemented purely in Python using
ctypes.Loosely-coupled to GeoDjango. For example,
GEOSGeometryobjects may be used outside of a Django project/application. In other words, no need to haveDJANGO_SETTINGS_MODULEset or use a database, etc.Mutability:
GEOSGeometryobjects may be modified.Cross-platform and tested; compatible with Windows, Linux, Solaris, and Mac OS X platforms.
TutorialLink to this heading
This section contains a brief introduction and tutorial to using
GEOSGeometry objects.
Creating a GeometryLink to this heading
GEOSGeometry objects may be created in a few ways. The first is
to simply instantiate the object on some spatial input – the following
are examples of creating the same geometry from WKT, HEX, WKB, and GeoJSON:
>>> from django.contrib.gis.geos import GEOSGeometry
>>> pnt = GEOSGeometry('POINT(5 23)') # WKT
>>> pnt = GEOSGeometry('010100000000000000000014400000000000003740') # HEX
>>> pnt = GEOSGeometry(buffer('\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x14@\x00\x00\x00\x00\x00\x007@'))
>>> pnt = GEOSGeometry('{ "type": "Point", "coordinates": [ 5.000000, 23.000000 ] }') # GeoJSON
Another option is to use the constructor for the specific geometry type
that you wish to create. For example, a Point object may be
created by passing in the X and Y coordinates into its constructor:
>>> from django.contrib.gis.geos import Point
>>> pnt = Point(5, 23)
All these constructors take the keyword argument srid. For example:
>>> from django.contrib.gis.geos import GEOSGeometry, LineString, Point
>>> print(GEOSGeometry('POINT (0 0)', srid=4326))
SRID=4326;POINT (0.0000000000000000 0.0000000000000000)
>>> print(LineString((0, 0), (1, 1), srid=4326))
SRID=4326;LINESTRING (0.0000000000000000 0.0000000000000000, 1.0000000000000000 1.0000000000000000)
>>> print(Point(0, 0, srid=32140))
SRID=32140;POINT (0.0000000000000000 0.0000000000000000)
Finally, there is the fromfile() factory method which returns a
GEOSGeometry object from a file:
>>> from django.contrib.gis.geos import fromfile
>>> pnt = fromfile('/path/to/pnt.wkt')
>>> pnt = fromfile(open('/path/to/pnt.wkt'))
Geometries are PythonicLink to this heading
GEOSGeometry objects are “Pythonic”, in other words components may
be accessed, modified, and iterated over using standard Python conventions.
For example, you can iterate over the coordinates in a Point:
>>> pnt = Point(5, 23)
>>> [coord for coord in pnt]
[5.0, 23.0]
With any geometry object, the GEOSGeometry.coords property
may be used to get the geometry coordinates as a Python tuple:
>>> pnt.coords
(5.0, 23.0)
You can get/set geometry components using standard Python indexing
techniques. However, what is returned depends on the geometry type
of the object. For example, indexing on a LineString
returns a coordinate tuple:
>>> from django.contrib.gis.geos import LineString
>>> line = LineString((0, 0), (0, 50), (50, 50), (50, 0), (0, 0))
>>> line[0]
(0.0, 0.0)
>>> line[-2]
(50.0, 0.0)
Whereas indexing on a Polygon will return the ring
(a LinearRing object) corresponding to the index:
>>> from django.contrib.gis.geos import Polygon
>>> poly = Polygon( ((0.0, 0.0), (0.0, 50.0), (50.0, 50.0), (50.0, 0.0), (0.0, 0.0)) )
>>> poly[0]
<LinearRing object at 0x1044395b0>
>>> poly[0][-2] # second-to-last coordinate of external ring
(50.0, 0.0)
In addition, coordinates/components of the geometry may added or modified, just like a Python list:
>>> line[0] = (1.0, 1.0)
>>> line.pop()
(0.0, 0.0)
>>> line.append((1.0, 1.0))
>>> line.coords
((1.0, 1.0), (0.0, 50.0), (50.0, 50.0), (50.0, 0.0), (1.0, 1.0))
Geometries support set-like operators:
>>> from django.contrib.gis.geos import LineString
>>> ls1 = LineString((0, 0), (2, 2))
>>> ls2 = LineString((1, 1), (3, 3))
>>> print(ls1 | ls2) # equivalent to `ls1.union(ls2)`
MULTILINESTRING ((0 0, 1 1), (1 1, 2 2), (2 2, 3 3))
>>> print(ls1 & ls2) # equivalent to `ls1.intersection(ls2)`
LINESTRING (1 1, 2 2)
>>> print(ls1 - ls2) # equivalent to `ls1.difference(ls2)`
LINESTRING(0 0, 1 1)
>>> print(ls1 ^ ls2) # equivalent to `ls1.sym_difference(ls2)`
MULTILINESTRING ((0 0, 1 1), (2 2, 3 3))
Geometry ObjectsLink to this heading
GEOSGeometryLink to this heading
- class GEOSGeometry(geo_input, srid=None)Link to this definition
- Parámetros:
geo_input – Geometry input value (string or buffer)
srid (int) – spatial reference identifier
This is the base class for all GEOS geometry objects. It initializes on the
given geo_input argument, and then assumes the proper geometry subclass
(e.g., GEOSGeometry('POINT(1 1)') will create a Point object).
The following input formats, along with their corresponding Python types, are accepted:
Format |
Input Type |
|---|---|
WKT / EWKT |
|
HEX / HEXEWKB |
|
WKB / EWKB |
|
GeoJSON (requires GDAL) |
|
PropertiesLink to this heading
- GEOSGeometry.coordsLink to this definition
Returns the coordinates of the geometry as a tuple.
- GEOSGeometry.dimsLink to this definition
Returns the dimension of the geometry:
0forPoints andMultiPoints1forLineStrings andMultiLineStrings2forPolygons andMultiPolygons-1for emptyGeometryCollectionsthe maximum dimension of its elements for non-empty
GeometryCollections
- GEOSGeometry.emptyLink to this definition
Returns whether or not the set of points in the geometry is empty.
- GEOSGeometry.geom_typeLink to this definition
Returns a string corresponding to the type of geometry. For example:
>>> pnt = GEOSGeometry('POINT(5 23)')
>>> pnt.geom_type
'Point'
- GEOSGeometry.geom_typeidLink to this definition
Returns the GEOS geometry type identification number. The following table shows the value for each geometry type:
Geometry |
ID |
|---|---|
0 |
|
1 |
|
2 |
|
3 |
|
4 |
|
5 |
|
6 |
|
7 |
- GEOSGeometry.num_coordsLink to this definition
Returns the number of coordinates in the geometry.
- GEOSGeometry.num_geomLink to this definition
Returns the number of geometries in this geometry. In other words, will return 1 on anything but geometry collections.
- GEOSGeometry.haszLink to this definition
Returns a boolean indicating whether the geometry is three-dimensional.
- GEOSGeometry.ringLink to this definition
Returns a boolean indicating whether the geometry is a LinearRing.
- GEOSGeometry.simpleLink to this definition
Returns a boolean indicating whether the geometry is “simple”. A geometry
is simple if and only if it does not intersect itself (except at boundary
points). For example, a LineString object is not simple if it
intersects itself. Thus, LinearRing and Polygon objects
are always simple because they do cannot intersect themselves, by
definition.
- GEOSGeometry.validLink to this definition
Returns a boolean indicating whether the geometry is valid.
- GEOSGeometry.valid_reasonLink to this definition
Returns a string describing the reason why a geometry is invalid.
- GEOSGeometry.sridLink to this definition
Property that may be used to retrieve or set the SRID associated with the geometry. For example:
>>> pnt = Point(5, 23)
>>> print(pnt.srid)
None
>>> pnt.srid = 4326
>>> pnt.srid
4326
Output PropertiesLink to this heading
The properties in this section export the GEOSGeometry object into
a different. This output may be in the form of a string, buffer, or even
another object.
- GEOSGeometry.ewktLink to this definition
Returns the «extended» Well-Known Text of the geometry. This representation
is specific to PostGIS and is a superset of the OGC WKT standard. [1]
Essentially the SRID is prepended to the WKT representation, for example
SRID=4326;POINT(5 23).
- GEOSGeometry.hexLink to this definition
Returns the WKB of this Geometry in hexadecimal form. Please note
that the SRID value is not included in this representation
because it is not a part of the OGC specification (use the
GEOSGeometry.hexewkb property instead).
- GEOSGeometry.hexewkbLink to this definition
Returns the EWKB of this Geometry in hexadecimal form. This is an extension of the WKB specification that includes the SRID value that are a part of this geometry.
- GEOSGeometry.jsonLink to this definition
Returns the GeoJSON representation of the geometry. Note that the result is not
a complete GeoJSON structure but only the geometry key content of a
GeoJSON structure. See also GeoJSON Serializer.
- GEOSGeometry.geojsonLink to this definition
Alias for GEOSGeometry.json.
- GEOSGeometry.kmlLink to this definition
Returns a KML (Keyhole Markup Language) representation of the geometry. This should only be used for geometries with an SRID of 4326 (WGS84), but this restriction is not enforced.
- GEOSGeometry.ogrLink to this definition
Returns an OGRGeometry object
corresponding to the GEOS geometry.
- GEOSGeometry.wkbLink to this definition
Returns the WKB (Well-Known Binary) representation of this Geometry
as a Python buffer. SRID value is not included, use the
GEOSGeometry.ewkb property instead.
- GEOSGeometry.ewkbLink to this definition
Return the EWKB representation of this Geometry as a Python buffer. This is an extension of the WKB specification that includes any SRID value that are a part of this geometry.
- GEOSGeometry.wktLink to this definition
Returns the Well-Known Text of the geometry (an OGC standard).
Spatial Predicate MethodsLink to this heading
All of the following spatial predicate methods take another
GEOSGeometry instance (other) as a parameter, and
return a boolean.
- GEOSGeometry.contains(other)Link to this definition
Returns True if other.within(this) returns
True.
- GEOSGeometry.crosses(other)Link to this definition
Returns True if the DE-9IM intersection matrix for the two Geometries
is T*T****** (for a point and a curve,a point and an area or a line
and an area) 0******** (for two curves).
- GEOSGeometry.disjoint(other)Link to this definition
Returns True if the DE-9IM intersection matrix for the two geometries
is FF*FF****.
- GEOSGeometry.equals(other)Link to this definition
Returns True if the DE-9IM intersection matrix for the two geometries
is T*F**FFF*.
- GEOSGeometry.equals_exact(other, tolerance=0)Link to this definition
Returns true if the two geometries are exactly equal, up to a
specified tolerance. The tolerance value should be a floating
point number representing the error tolerance in the comparison, e.g.,
poly1.equals_exact(poly2, 0.001) will compare equality to within
one thousandth of a unit.
- GEOSGeometry.intersects(other)Link to this definition
Returns True if GEOSGeometry.disjoint() is False.
- GEOSGeometry.overlaps(other)Link to this definition
Returns true if the DE-9IM intersection matrix for the two geometries
is T*T***T** (for two points or two surfaces) 1*T***T**
(for two curves).
- GEOSGeometry.relate_pattern(other, pattern)Link to this definition
Returns True if the elements in the DE-9IM intersection matrix
for this geometry and the other matches the given pattern –
a string of nine characters from the alphabet: {T, F, *, 0}.
- GEOSGeometry.touches(other)Link to this definition
Returns True if the DE-9IM intersection matrix for the two geometries
is FT*******, F**T***** or F***T****.
- GEOSGeometry.within(other)Link to this definition
Returns True if the DE-9IM intersection matrix for the two geometries
is T*F**F***.
Topological MethodsLink to this heading
- GEOSGeometry.buffer(width, quadsegs=8)Link to this definition
Returns a GEOSGeometry that represents all points whose distance
from this geometry is less than or equal to the given width. The optional
quadsegs keyword sets the number of segments used to approximate a
quarter circle (defaults is 8).
- GEOSGeometry.difference(other)Link to this definition
Returns a GEOSGeometry representing the points making up this
geometry that do not make up other.
- GEOSGeometry.interpolate(distance)Link to this definition
- GEOSGeometry.interpolate_normalized(distance)Link to this definition
Given a distance (float), returns the point (or closest point) within the
geometry (LineString or MultiLineString) at that distance.
The normalized version takes the distance as a float between 0 (origin) and 1
(endpoint).
Reverse of GEOSGeometry.project().
- GEOSGeometry.intersection(other)Link to this definition
Returns a GEOSGeometry representing the points shared by this
geometry and other.
- GEOSGeometry.project(point)Link to this definition
- GEOSGeometry.project_normalized(point)Link to this definition
Returns the distance (float) from the origin of the geometry
(LineString or MultiLineString) to the point projected on the
geometry (that is to a point of the line the closest to the given point).
The normalized version returns the distance as a float between 0 (origin) and 1
(endpoint).
Reverse of GEOSGeometry.interpolate().
- GEOSGeometry.relate(other)Link to this definition
Returns the DE-9IM intersection matrix (a string) representing the topological relationship between this geometry and the other.
- GEOSGeometry.simplify(tolerance=0.0, preserve_topology=False)Link to this definition
Returns a new GEOSGeometry, simplified to the specified tolerance
using the Douglas-Peucker algorithm. A higher tolerance value implies
fewer points in the output. If no tolerance is provided, it defaults to 0.
By default, this function does not preserve topology. For example,
Polygon objects can be split, be collapsed into lines, or disappear.
Polygon holes can be created or disappear, and lines may cross.
By specifying preserve_topology=True, the result will have the same
dimension and number of components as the input; this is significantly
slower, however.
- GEOSGeometry.sym_difference(other)Link to this definition
Returns a GEOSGeometry combining the points in this geometry
not in other, and the points in other not in this geometry.
- GEOSGeometry.union(other)Link to this definition
Returns a GEOSGeometry representing all the points in this
geometry and the other.
Topological PropertiesLink to this heading
- GEOSGeometry.boundaryLink to this definition
Returns the boundary as a newly allocated Geometry object.
- GEOSGeometry.centroidLink to this definition
Returns a Point object representing the geometric center of
the geometry. The point is not guaranteed to be on the interior
of the geometry.
- GEOSGeometry.convex_hullLink to this definition
Returns the smallest Polygon that contains all the points in
the geometry.
- GEOSGeometry.envelopeLink to this definition
Returns a Polygon that represents the bounding envelope of
this geometry. Note that it can also return a Point if the input
geometry is a point.
- GEOSGeometry.point_on_surfaceLink to this definition
Computes and returns a Point guaranteed to be on the interior
of this geometry.
Other Properties & MethodsLink to this heading
- GEOSGeometry.areaLink to this definition
This property returns the area of the Geometry.
- GEOSGeometry.extentLink to this definition
This property returns the extent of this geometry as a 4-tuple,
consisting of (xmin, ymin, xmax, ymax).
- GEOSGeometry.clone()Link to this definition
This method returns a GEOSGeometry that is a clone of the original.
- GEOSGeometry.distance(geom)Link to this definition
Returns the distance between the closest points on this geometry and the given
geom (another GEOSGeometry object).
- GEOSGeometry.lengthLink to this definition
Returns the length of this geometry (e.g., 0 for a Point,
the length of a LineString, or the circumference of
a Polygon).
- GEOSGeometry.preparedLink to this definition
Returns a GEOS PreparedGeometry for the contents of this geometry.
PreparedGeometry objects are optimized for the contains, intersects,
covers, crosses, disjoint, overlaps, touches and within operations. Refer to
the Prepared Geometries documentation for more information.
- GEOSGeometry.srsLink to this definition
Returns a SpatialReference object
corresponding to the SRID of the geometry or None.
- GEOSGeometry.transform(ct, clone=False)Link to this definition
Transforms the geometry according to the given coordinate transformation parameter
(ct), which may be an integer SRID, spatial reference WKT string,
a PROJ.4 string, a SpatialReference object, or a
CoordTransform object. By default, the geometry
is transformed in-place and nothing is returned. However if the clone keyword
is set, then the geometry is not modified and a transformed clone of the geometry
is returned instead.
PointLink to this heading
- class Point(x, y, z=None, srid=None)Link to this definition
Pointobjects are instantiated using arguments that represent the component coordinates of the point or with a single sequence coordinates. For example, the following are equivalent:>>> pnt = Point(5, 23) >>> pnt = Point([5, 23])
LineStringLink to this heading
- class LineString(*args, **kwargs)Link to this definition
LineStringobjects are instantiated using arguments that are either a sequence of coordinates orPointobjects. For example, the following are equivalent:>>> ls = LineString((0, 0), (1, 1)) >>> ls = LineString(Point(0, 0), Point(1, 1))In addition,
LineStringobjects may also be created by passing in a single sequence of coordinate orPointobjects:>>> ls = LineString( ((0, 0), (1, 1)) ) >>> ls = LineString( [Point(0, 0), Point(1, 1)] )
LinearRingLink to this heading
- class LinearRing(*args, **kwargs)Link to this definition
LinearRingobjects are constructed in the exact same way asLineStringobjects, however the coordinates must be closed, in other words, the first coordinates must be the same as the last coordinates. For example:>>> ls = LinearRing((0, 0), (0, 1), (1, 1), (0, 0))Notice that
(0, 0)is the first and last coordinate – if they were not equal, an error would be raised.
PolygonLink to this heading
- class Polygon(*args, **kwargs)Link to this definition
Polygonobjects may be instantiated by passing in one or more parameters that represent the rings of the polygon. The parameters must either beLinearRinginstances, or a sequence that may be used to construct aLinearRing:>>> ext_coords = ((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)) >>> int_coords = ((0.4, 0.4), (0.4, 0.6), (0.6, 0.6), (0.6, 0.4), (0.4, 0.4)) >>> poly = Polygon(ext_coords, int_coords) >>> poly = Polygon(LinearRing(ext_coords), LinearRing(int_coords))- classmethod from_bbox(bbox)Link to this definition
Returns a polygon object from the given bounding-box, a 4-tuple comprising
(xmin, ymin, xmax, ymax).- num_interior_ringsLink to this definition
Returns the number of interior rings in this geometry.
Geometry CollectionsLink to this heading
MultiPointLink to this heading
- class MultiPoint(*args, **kwargs)Link to this definition
MultiPointobjects may be instantiated by passing in one or morePointobjects as arguments, or a single sequence ofPointobjects:>>> mp = MultiPoint(Point(0, 0), Point(1, 1)) >>> mp = MultiPoint( (Point(0, 0), Point(1, 1)) )
MultiLineStringLink to this heading
- class MultiLineString(*args, **kwargs)Link to this definition
MultiLineStringobjects may be instantiated by passing in one or moreLineStringobjects as arguments, or a single sequence ofLineStringobjects:>>> ls1 = LineString((0, 0), (1, 1)) >>> ls2 = LineString((2, 2), (3, 3)) >>> mls = MultiLineString(ls1, ls2) >>> mls = MultiLineString([ls1, ls2])- mergedLink to this definition
Returns a
LineStringrepresenting the line merge of all the components in thisMultiLineString.
MultiPolygonLink to this heading
- class MultiPolygon(*args, **kwargs)Link to this definition
MultiPolygonobjects may be instantiated by passing one or morePolygonobjects as arguments, or a single sequence ofPolygonobjects:>>> p1 = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) ) >>> p2 = Polygon( ((1, 1), (1, 2), (2, 2), (1, 1)) ) >>> mp = MultiPolygon(p1, p2) >>> mp = MultiPolygon([p1, p2])- cascaded_unionLink to this definition
Returns a
Polygonthat is the union of all of the component polygons in this collection. The algorithm employed is significantly more efficient (faster) than trying to union the geometries together individually. [2]
GeometryCollectionLink to this heading
- class GeometryCollection(*args, **kwargs)Link to this definition
GeometryCollectionobjects may be instantiated by passing in one or more otherGEOSGeometryas arguments, or a single sequence ofGEOSGeometryobjects:>>> poly = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) ) >>> gc = GeometryCollection(Point(0, 0), MultiPoint(Point(0, 0), Point(1, 1)), poly) >>> gc = GeometryCollection((Point(0, 0), MultiPoint(Point(0, 0), Point(1, 1)), poly))
Prepared GeometriesLink to this heading
In order to obtain a prepared geometry, just access the
GEOSGeometry.prepared property. Once you have a
PreparedGeometry instance its spatial predicate methods, listed below,
may be used with other GEOSGeometry objects. An operation with a prepared
geometry can be orders of magnitude faster – the more complex the geometry
that is prepared, the larger the speedup in the operation. For more information,
please consult the GEOS wiki page on prepared geometries.
For example:
>>> from django.contrib.gis.geos import Point, Polygon
>>> poly = Polygon.from_bbox((0, 0, 5, 5))
>>> prep_poly = poly.prepared
>>> prep_poly.contains(Point(2.5, 2.5))
True
PreparedGeometryLink to this heading
- class PreparedGeometryLink to this definition
All methods on
PreparedGeometrytake anotherargument, which must be aGEOSGeometryinstance.- contains(other)Link to this definition
- contains_properly(other)Link to this definition
- covers(other)Link to this definition
- crosses(other)Link to this definition
- disjoint(other)Link to this definition
- intersects(other)Link to this definition
- overlaps(other)Link to this definition
- touches(other)Link to this definition
- within(other)Link to this definition
Geometry FactoriesLink to this heading
- fromfile(file_h)Link to this definition
- Parámetros:
file_h (a Python
fileobject or a string path to the file) – input file that contains spatial data- Tipo del valor devuelto:
a
GEOSGeometrycorresponding to the spatial data in the file
Example:
>>> from django.contrib.gis.geos import fromfile
>>> g = fromfile('/home/bob/geom.wkt')
- fromstr(string, srid=None)Link to this definition
- Parámetros:
string (string) – string that contains spatial data
srid (int) – spatial reference identifier
- Tipo del valor devuelto:
a
GEOSGeometrycorresponding to the spatial data in the string
fromstr(string, srid) is equivalent to GEOSGeometry(string, srid).
Example:
>>> from django.contrib.gis.geos import fromstr
>>> pnt = fromstr('POINT(-90.5 29.5)', srid=4326)
I/O ObjectsLink to this heading
Reader ObjectsLink to this heading
The reader I/O classes simply return a GEOSGeometry instance from the
WKB and/or WKT input given to their read(geom) method.
- class WKBReaderLink to this definition
Example:
>>> from django.contrib.gis.geos import WKBReader
>>> wkb_r = WKBReader()
>>> wkb_r.read('0101000000000000000000F03F000000000000F03F')
<Point object at 0x103a88910>
- class WKTReaderLink to this definition
Example:
>>> from django.contrib.gis.geos import WKTReader
>>> wkt_r = WKTReader()
>>> wkt_r.read('POINT(1 1)')
<Point object at 0x103a88b50>
Writer ObjectsLink to this heading
All writer objects have a write(geom) method that returns either the
WKB or WKT of the given geometry. In addition, WKBWriter objects
also have properties that may be used to change the byte order, and or
include the SRID value (in other words, EWKB).
- class WKBWriterLink to this definition
WKBWriter provides the most control over its output. By default it
returns OGC-compliant WKB when its write method is called. However,
it has properties that allow for the creation of EWKB, a superset of the
WKB standard that includes additional information.
- WKBWriter.write(geom)Link to this definition
Returns the WKB of the given geometry as a Python buffer object.
Example:
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> pnt = Point(1, 1)
>>> wkb_w = WKBWriter()
>>> wkb_w.write(pnt)
<read-only buffer for 0x103a898f0, size -1, offset 0 at 0x103a89930>
- WKBWriter.write_hex(geom)Link to this definition
Returns WKB of the geometry in hexadecimal. Example:
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> pnt = Point(1, 1)
>>> wkb_w = WKBWriter()
>>> wkb_w.write_hex(pnt)
'0101000000000000000000F03F000000000000F03F'
- WKBWriter.byteorderLink to this definition
This property may be set to change the byte-order of the geometry representation.
Byteorder Value |
Description |
|---|---|
0 |
Big Endian (e.g., compatible with RISC systems) |
1 |
Little Endian (e.g., compatible with x86 systems) |
Example:
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
>>> pnt = Point(1, 1)
>>> wkb_w.write_hex(pnt)
'0101000000000000000000F03F000000000000F03F'
>>> wkb_w.byteorder = 0
'00000000013FF00000000000003FF0000000000000'
- WKBWriter.outdimLink to this definition
This property may be set to change the output dimension of the geometry representation. In other words, if you have a 3D geometry then set to 3 so that the Z value is included in the WKB.
Outdim Value |
Description |
|---|---|
2 |
The default, output 2D WKB. |
3 |
Output 3D WKB. |
Example:
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
>>> wkb_w.outdim
2
>>> pnt = Point(1, 1, 1)
>>> wkb_w.write_hex(pnt) # By default, no Z value included:
'0101000000000000000000F03F000000000000F03F'
>>> wkb_w.outdim = 3 # Tell writer to include Z values
>>> wkb_w.write_hex(pnt)
'0101000080000000000000F03F000000000000F03F000000000000F03F'
- WKBWriter.sridLink to this definition
Set this property with a boolean to indicate whether the SRID of the geometry should be included with the WKB representation. Example:
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
>>> pnt = Point(1, 1, srid=4326)
>>> wkb_w.write_hex(pnt) # By default, no SRID included:
'0101000000000000000000F03F000000000000F03F'
>>> wkb_w.srid = True # Tell writer to include SRID
>>> wkb_w.write_hex(pnt)
'0101000020E6100000000000000000F03F000000000000F03F'
- class WKTWriterLink to this definition
- WKTWriter.write(geom)Link to this definition
Returns the WKT of the given geometry. Example:
>>> from django.contrib.gis.geos import Point, WKTWriter
>>> pnt = Point(1, 1)
>>> wkt_w = WKTWriter()
>>> wkt_w.write(pnt)
'POINT (1.0000000000000000 1.0000000000000000)'
Footnotes
SettingsLink to this heading
GEOS_LIBRARY_PATHLink to this heading
A string specifying the location of the GEOS C library. Typically,
this setting is only used if the GEOS C library is in a non-standard
location (e.g., /home/bob/lib/libgeos_c.so).
Nota
The setting must be the full path to the C shared library; in
other words you want to use libgeos_c.so, not libgeos.so.
ExceptionsLink to this heading
- exception GEOSExceptionLink to this definition
The base GEOS exception, indicates a GEOS-related error.