GeoQuerySet API Reference¶
- class GeoQuerySet([model=None])¶
Spatial Lookups¶
Just like when using the QuerySet API, interaction with GeoQuerySet by chaining filters. Instead of the regular Django Field lookups, the spatial lookups in this section are available for GeometryField.
For an introduction, see the spatial lookups introduction. For an overview of what lookups are compatible with a particular spatial backend, refer to the spatial lookup compatibility table.
bbcontains¶
Availability: PostGIS, MySQL, SpatiaLite
Tests if the geometry field’s bounding box completely contains the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__bbcontains=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | poly ~ geom |
MySQL | MBRContains(poly, geom) |
SpatiaLite | MbrContains(poly, geom) |
bboverlaps¶
Availability: PostGIS, MySQL, SpatiaLite
Tests if the geometry field’s bounding box overlaps the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__bboverlaps=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | poly && geom |
MySQL | MBROverlaps(poly, geom) |
SpatiaLite | MbrOverlaps(poly, geom) |
contained¶
Availability: PostGIS, MySQL, SpatiaLite
Tests if the geometry field’s bounding box is completely contained by the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__contained=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | poly @ geom |
MySQL | MBRWithin(poly, geom) |
SpatiaLite | MbrWithin(poly, geom) |
contains¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
Tests if the geometry field spatially contains the lookup geometry.
Example:
Zipcode.objects.filter(poly__contains=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Contains(poly, geom) |
Oracle | SDO_CONTAINS(poly, geom) |
MySQL | MBRContains(poly, geom) |
SpatiaLite | Contains(poly, geom) |
contains_properly¶
Availability: PostGIS
Returns true if the lookup geometry intersects the interior of the geometry field, but not the boundary (or exterior). [4]
Example:
Zipcode.objects.filter(poly__contains_properly=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_ContainsProperly(poly, geom) |
coveredby¶
Availability: PostGIS, Oracle
Tests if no point in the geometry field is outside the lookup geometry. [3]
Example:
Zipcode.objects.filter(poly__coveredby=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_CoveredBy(poly, geom) |
Oracle | SDO_COVEREDBY(poly, geom) |
covers¶
Availability: PostGIS, Oracle
Tests if no point in the lookup geometry is outside the geometry field. [3]
Example:
Zipcode.objects.filter(poly__covers=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Covers(poly, geom) |
Oracle | SDO_COVERS(poly, geom) |
crosses¶
Availability: PostGIS, SpatiaLite
Tests if the geometry field spatially crosses the lookup geometry.
Example:
Zipcode.objects.filter(poly__crosses=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Crosses(poly, geom) |
SpatiaLite | Crosses(poly, geom) |
disjoint¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
Tests if the geometry field is spatially disjoint from the lookup geometry.
Example:
Zipcode.objects.filter(poly__disjoint=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Disjoint(poly, geom) |
Oracle | SDO_GEOM.RELATE(poly, 'DISJOINT', geom, 0.05) |
MySQL | MBRDisjoint(poly, geom) |
SpatiaLite | Disjoint(poly, geom) |
equals¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
exact, same_as¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
intersects¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
Tests if the geometry field spatially intersects the lookup geometry.
Example:
Zipcode.objects.filter(poly__intersects=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Intersects(poly, geom) |
Oracle | SDO_OVERLAPBDYINTERSECT(poly, geom) |
MySQL | MBRIntersects(poly, geom) |
SpatiaLite | Intersects(poly, geom) |
overlaps¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
relate¶
Availability: PostGIS, Oracle, SpatiaLite
Tests if the geometry field is spatially related to the lookup geometry by the values given in the given pattern. This lookup requires a tuple parameter, (geom, pattern); the form of pattern will depend on the spatial backend:
PostGIS & SpatiaLite¶
On these spatial backends the intersection pattern is a string comprising nine characters, which define intersections between the interior, boundary, and exterior of the geometry field and the lookup geometry. The intersection pattern matrix may only use the following characters: 1, 2, T, F, or *. This lookup type allows users to “fine tune” a specific geometric relationship consistent with the DE-9IM model. [1]
Example:
# A tuple lookup parameter is used to specify the geometry and
# the intersection pattern (the pattern here is for 'contains').
Zipcode.objects.filter(poly__relate=(geom, 'T*T***FF*'))
PostGIS SQL equivalent:
SELECT ... WHERE ST_Relate(poly, geom, 'T*T***FF*')
SpatiaLite SQL equivalent:
SELECT ... WHERE Relate(poly, geom, 'T*T***FF*')
Oracle¶
Here the relation pattern is comprised at least one of the nine relation strings: TOUCH, OVERLAPBDYDISJOINT, OVERLAPBDYINTERSECT, EQUAL, INSIDE, COVEREDBY, CONTAINS, COVERS, ON, and ANYINTERACT. Multiple strings may be combined with the logical Boolean operator OR, for example, 'inside+touch'. [2] The relation strings are case-insensitive.
Example:
Zipcode.objects.filter(poly__relate=(geom, 'anyinteract'))
Oracle SQL equivalent:
SELECT ... WHERE SDO_RELATE(poly, geom, 'anyinteract')
touches¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
Tests if the geometry field spatially touches the lookup geometry.
Example:
Zipcode.objects.filter(poly__touches=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Touches(poly, geom) |
MySQL | MBRTouches(poly, geom) |
Oracle | SDO_TOUCH(poly, geom) |
SpatiaLite | Touches(poly, geom) |
within¶
Availability: PostGIS, Oracle, MySQL, SpatiaLite
Tests if the geometry field is spatially within the lookup geometry.
Example:
Zipcode.objects.filter(poly__within=geom)
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Within(poly, geom) |
MySQL | MBRWithin(poly, geom) |
Oracle | SDO_INSIDE(poly, geom) |
SpatiaLite | Within(poly, geom) |
left¶
Availability: PostGIS
Tests if the geometry field’s bounding box is strictly to the left of the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__left=geom)
PostGIS equivalent:
SELECT ... WHERE poly << geom
right¶
Availability: PostGIS
Tests if the geometry field’s bounding box is strictly to the right of the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__right=geom)
PostGIS equivalent:
SELECT ... WHERE poly >> geom
overlaps_left¶
Availability: PostGIS
Tests if the geometry field’s bounding box overlaps or is to the left of the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__overlaps_left=geom)
PostGIS equivalent:
SELECT ... WHERE poly &< geom
overlaps_right¶
Availability: PostGIS
Tests if the geometry field’s bounding box overlaps or is to the right of the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__overlaps_right=geom)
PostGIS equivalent:
SELECT ... WHERE poly &> geom
overlaps_above¶
Availability: PostGIS
Tests if the geometry field’s bounding box overlaps or is above the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__overlaps_above=geom)
PostGIS equivalent:
SELECT ... WHERE poly |&> geom
overlaps_below¶
Availability: PostGIS
Tests if the geometry field’s bounding box overlaps or is below the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__overlaps_below=geom)
PostGIS equivalent:
SELECT ... WHERE poly &<| geom
strictly_above¶
Availability: PostGIS
Tests if the geometry field’s bounding box is strictly above the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__strictly_above=geom)
PostGIS equivalent:
SELECT ... WHERE poly |>> geom
strictly_below¶
Availability: PostGIS
Tests if the geometry field’s bounding box is strictly below the lookup geometry’s bounding box.
Example:
Zipcode.objects.filter(poly__strictly_below=geom)
PostGIS equivalent:
SELECT ... WHERE poly <<| geom
Distance Lookups¶
Availability: PostGIS, Oracle, SpatiaLite
For an overview on performing distance queries, please refer to the distance queries introduction.
Distance lookups take the following form:
<field>__<distance lookup>=(<geometry>, <distance value>[, 'spheroid'])
The value passed into a distance lookup is a tuple; the first two values are mandatory, and are the geometry to calculate distances to, and a distance value (either a number in units of the field or a Distance object). On every distance lookup but dwithin, an optional third element, 'spheroid', may be included to tell GeoDjango to use the more accurate spheroid distance calculation functions on fields with a geodetic coordinate system (e.g., ST_Distance_Spheroid would be used instead of ST_Distance_Sphere).
distance_gt¶
Returns models where the distance to the geometry field from the lookup geometry is greater than the given distance value.
Example:
Zipcode.objects.filter(poly__distance_gt=(geom, D(m=5)))
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Distance(poly, geom) > 5 |
Oracle | SDO_GEOM.SDO_DISTANCE(poly, geom, 0.05) > 5 |
SpatiaLite | Distance(poly, geom) > 5 |
distance_gte¶
Returns models where the distance to the geometry field from the lookup geometry is greater than or equal to the given distance value.
Example:
Zipcode.objects.filter(poly__distance_gte=(geom, D(m=5)))
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Distance(poly, geom) >= 5 |
Oracle | SDO_GEOM.SDO_DISTANCE(poly, geom, 0.05) >= 5 |
SpatiaLite | Distance(poly, geom) >= 5 |
distance_lt¶
Returns models where the distance to the geometry field from the lookup geometry is less than the given distance value.
Example:
Zipcode.objects.filter(poly__distance_lt=(geom, D(m=5)))
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Distance(poly, geom) < 5 |
Oracle | SDO_GEOM.SDO_DISTANCE(poly, geom, 0.05) < 5 |
SpatiaLite | Distance(poly, geom) < 5 |
distance_lte¶
Returns models where the distance to the geometry field from the lookup geometry is less than or equal to the given distance value.
Example:
Zipcode.objects.filter(poly__distance_lte=(geom, D(m=5)))
Backend | SQL Equivalent |
---|---|
PostGIS | ST_Distance(poly, geom) <= 5 |
Oracle | SDO_GEOM.SDO_DISTANCE(poly, geom, 0.05) <= 5 |
SpatiaLite | Distance(poly, geom) <= 5 |
dwithin¶
Returns models where the distance to the geometry field from the lookup geometry are within the given distance from one another. Note that you can only provide Distance objects if the targeted geometries are in a projected system. For geographic geometries, you should use units of the geometry field (e.g. degrees for WGS84) .
Example:
Zipcode.objects.filter(poly__dwithin=(geom, D(m=5)))
Backend | SQL Equivalent |
---|---|
PostGIS | ST_DWithin(poly, geom, 5) |
Oracle | SDO_WITHIN_DISTANCE(poly, geom, 5) |
Note
This lookup is not available on SpatiaLite.
GeoQuerySet Methods¶
Deprecated since version 1.9: Using GeoQuerySet methods is now deprecated in favor of the new Geographic Database Functions. Albeit a little more verbose, they are much more powerful in how it is possible to combine them to build more complex queries.
GeoQuerySet methods specify that a spatial operation be performed on each spatial operation on each geographic field in the queryset and store its output in a new attribute on the model (which is generally the name of the GeoQuerySet method).
There are also aggregate GeoQuerySet methods which return a single value instead of a queryset. This section will describe the API and availability of every GeoQuerySet method available in GeoDjango.
Note
What methods are available depend on your spatial backend. See the compatibility table for more details.
With a few exceptions, the following keyword arguments may be used with all GeoQuerySet methods:
Keyword Argument | Description |
---|---|
field_name | By default, GeoQuerySet methods use the first geographic field encountered in the model. This keyword should be used to specify another geographic field (e.g., field_name='point2') when there are multiple geographic fields in a model. On PostGIS, the field_name keyword may also be used on geometry fields in models that are related via a ForeignKey relation (e.g., field_name='related__point'). |
model_att | By default, GeoQuerySet methods typically attach their output in an attribute with the same name as the GeoQuerySet method. Setting this keyword with the desired attribute name will override this default behavior. For example, qs = Zipcode.objects.centroid(model_att='c') will attach the centroid of the Zipcode geometry field in a c attribute on every model rather than in a centroid attribute. This keyword is required if a method name clashes with an existing GeoQuerySet method – if you wanted to use the area() method on model with a PolygonField named area, for example. |
Measurement¶
Availability: PostGIS, Oracle, SpatiaLite
area¶
- GeoQuerySet.area(**kwargs)¶
Deprecated since version 1.9: Use the Area function instead.
Returns the area of the geographic field in an area attribute on each element of this GeoQuerySet.
distance¶
- GeoQuerySet.distance(geom, **kwargs)¶
Deprecated since version 1.9: Use the Distance function instead.
This method takes a geometry as a parameter, and attaches a distance attribute to every model in the returned queryset that contains the distance (as a Distance object) to the given geometry.
In the following example (taken from the GeoDjango distance tests), the distance from the Tasmanian city of Hobart to every other PointField in the AustraliaCity queryset is calculated:
>>> pnt = AustraliaCity.objects.get(name='Hobart').point
>>> for city in AustraliaCity.objects.distance(pnt): print(city.name, city.distance)
Wollongong 990071.220408 m
Shellharbour 972804.613941 m
Thirroul 1002334.36351 m
Mittagong 975691.632637 m
Batemans Bay 834342.185561 m
Canberra 598140.268959 m
Melbourne 575337.765042 m
Sydney 1056978.87363 m
Hobart 0.0 m
Adelaide 1162031.83522 m
Hillsdale 1049200.46122 m
Note
Because the distance attribute is a Distance object, you can easily express the value in the units of your choice. For example, city.distance.mi is the distance value in miles and city.distance.km is the distance value in kilometers. See Measurement Objects for usage details and the list of Supported units.
Geometry Relationships¶
The following methods take no arguments, and attach geometry objects each element of the GeoQuerySet that is the result of relationship function evaluated on the geometry field.
centroid¶
- GeoQuerySet.centroid(**kwargs)¶
Deprecated since version 1.9: Use the Centroid function instead.
Availability: PostGIS, Oracle, SpatiaLite
Returns the centroid value for the geographic field in a centroid attribute on each element of the GeoQuerySet.
envelope¶
- GeoQuerySet.envelope(**kwargs)¶
Deprecated since version 1.9: Use the Envelope function instead.
Availability: PostGIS, SpatiaLite
Returns a geometry representing the bounding box of the geometry field in an envelope attribute on each element of the GeoQuerySet.
point_on_surface¶
- GeoQuerySet.point_on_surface(**kwargs)¶
Deprecated since version 1.9: Use the PointOnSurface function instead.
Availability: PostGIS, Oracle, SpatiaLite
Returns a Point geometry guaranteed to lie on the surface of the geometry field in a point_on_surface attribute on each element of the queryset; otherwise sets with None.
Geometry Editors¶
force_rhr¶
- GeoQuerySet.force_rhr(**kwargs)¶
Deprecated since version 1.9: Use the ForceRHR function instead.
Availability: PostGIS
Returns a modified version of the polygon/multipolygon in which all of the vertices follow the Right-Hand-Rule, and attaches as a force_rhr attribute on each element of the queryset.
reverse_geom¶
- GeoQuerySet.reverse_geom(**kwargs)¶
Deprecated since version 1.9: Use the Reverse function instead.
Availability: PostGIS, Oracle
Reverse the coordinate order of the geometry field, and attaches as a reverse attribute on each element of the queryset.
scale¶
- GeoQuerySet.scale(x, y, z=0.0, **kwargs)¶
Deprecated since version 1.9: Use the Scale function instead.
Availability: PostGIS, SpatiaLite
snap_to_grid¶
- GeoQuerySet.snap_to_grid(*args, **kwargs)¶
Deprecated since version 1.9: Use the SnapToGrid function instead.
Snap all points of the input geometry to the grid. How the geometry is snapped to the grid depends on how many numeric (either float, integer, or long) arguments are given.
Number of Arguments | Description |
---|---|
1 | A single size to snap bot the X and Y grids to. |
2 | X and Y sizes to snap the grid to. |
4 | X, Y sizes and the corresponding X, Y origins. |
transform¶
- GeoQuerySet.transform(srid=4326, **kwargs)¶
Deprecated since version 1.9: Use the Transform function instead.
Availability: PostGIS, Oracle, SpatiaLite
The transform method transforms the geometry field of a model to the spatial reference system specified by the srid parameter. If no srid is given, then 4326 (WGS84) is used by default.
Note
Unlike other GeoQuerySet methods, transform stores its output “in-place”. In other words, no new attribute for the transformed geometry is placed on the models.
Note
What spatial reference system an integer SRID corresponds to may depend on the spatial database used. In other words, the SRID numbers used for Oracle are not necessarily the same as those used by PostGIS.
Example:
>>> qs = Zipcode.objects.all().transform() # Transforms to WGS84
>>> qs = Zipcode.objects.all().transform(32140) # Transforming to "NAD83 / Texas South Central"
>>> print(qs[0].poly.srid)
32140
>>> print(qs[0].poly)
POLYGON ((234055.1698884720099159 4937796.9232223574072123 ...
Geometry Operations¶
Availability: PostGIS, Oracle, SpatiaLite
The following methods all take a geometry as a parameter and attach a geometry to each element of the GeoQuerySet that is the result of the operation.
difference¶
- GeoQuerySet.difference(geom)¶
Deprecated since version 1.9: Use the Difference function instead.
Returns the spatial difference of the geographic field with the given geometry in a difference attribute on each element of the GeoQuerySet.
intersection¶
- GeoQuerySet.intersection(geom)¶
Deprecated since version 1.9: Use the Intersection function instead.
Returns the spatial intersection of the geographic field with the given geometry in an intersection attribute on each element of the GeoQuerySet.
sym_difference¶
- GeoQuerySet.sym_difference(geom)¶
Deprecated since version 1.9: Use the SymDifference function instead.
Returns the symmetric difference of the geographic field with the given geometry in a sym_difference attribute on each element of the GeoQuerySet.
Geometry Output¶
The following GeoQuerySet methods will return an attribute that has the value of the geometry field in each model converted to the requested output format.
geohash¶
- GeoQuerySet.geohash(precision=20, **kwargs)¶
Deprecated since version 1.9: Use the GeoHash function instead.
Attaches a geohash attribute to every model the queryset containing the GeoHash representation of the geometry.
geojson¶
- GeoQuerySet.geojson(**kwargs)¶
Deprecated since version 1.9: Use the AsGeoJSON function instead.
Availability: PostGIS, SpatiaLite
Attaches a geojson attribute to every model in the queryset that contains the GeoJSON representation of the geometry.
Keyword Argument | Description |
---|---|
precision | It may be used to specify the number of significant digits for the coordinates in the GeoJSON representation – the default value is 8. |
crs | Set this to True if you want the coordinate reference system to be included in the returned GeoJSON. |
bbox | Set this to True if you want the bounding box to be included in the returned GeoJSON. |
gml¶
- GeoQuerySet.gml(**kwargs)¶
Deprecated since version 1.9: Use the AsGML function instead.
Availability: PostGIS, Oracle, SpatiaLite
Attaches a gml attribute to every model in the queryset that contains the Geographic Markup Language (GML) representation of the geometry.
Example:
>>> qs = Zipcode.objects.all().gml()
>>> print(qs[0].gml)
<gml:Polygon srsName="EPSG:4326"><gml:OuterBoundaryIs>-147.78711,70.245363 ... -147.78711,70.245363</gml:OuterBoundaryIs></gml:Polygon>
Keyword Argument | Description |
---|---|
precision | This keyword is for PostGIS only. It may be used to specify the number of significant digits for the coordinates in the GML representation – the default value is 8. |
version | This keyword is for PostGIS only. It may be used to specify the GML version used, and may only be values of 2 or 3. The default value is 2. |
kml¶
- GeoQuerySet.kml(**kwargs)¶
Deprecated since version 1.9: Use the AsKML function instead.
Availability: PostGIS, SpatiaLite
Attaches a kml attribute to every model in the queryset that contains the Keyhole Markup Language (KML) representation of the geometry fields. It should be noted that the contents of the KML are transformed to WGS84 if necessary.
Example:
>>> qs = Zipcode.objects.all().kml()
>>> print(qs[0].kml)
<Polygon><outerBoundaryIs><LinearRing><coordinates>-103.04135,36.217596,0 ... -103.04135,36.217596,0</coordinates></LinearRing></outerBoundaryIs></Polygon>
Keyword Argument | Description |
---|---|
precision | This keyword may be used to specify the number of significant digits for the coordinates in the KML representation – the default value is 8. |
svg¶
- GeoQuerySet.svg(**kwargs)¶
Deprecated since version 1.9: Use the AsSVG function instead.
Availability: PostGIS, SpatiaLite
Attaches a svg attribute to every model in the queryset that contains the Scalable Vector Graphics (SVG) path data of the geometry fields.
Keyword Argument | Description |
---|---|
relative | If set to True, the path data will be implemented in terms of relative moves. Defaults to False, meaning that absolute moves are used instead. |
precision | This keyword may be used to specify the number of significant digits for the coordinates in the SVG representation – the default value is 8. |
Miscellaneous¶
mem_size¶
- GeoQuerySet.mem_size(**kwargs)¶
Deprecated since version 1.9: Use the MemSize function instead.
Availability: PostGIS
Returns the memory size (number of bytes) that the geometry field takes in a mem_size attribute on each element of the GeoQuerySet.
num_geom¶
- GeoQuerySet.num_geom(**kwargs)¶
Deprecated since version 1.9: Use the NumGeometries function instead.
Availability: PostGIS, Oracle, SpatiaLite
Returns the number of geometries in a num_geom attribute on each element of the GeoQuerySet if the geometry field is a collection (e.g., a GEOMETRYCOLLECTION or MULTI* field); otherwise sets with None.
num_points¶
- GeoQuerySet.num_points(**kwargs)¶
Deprecated since version 1.9: Use the NumPoints function instead.
Availability: PostGIS, Oracle, SpatiaLite
Returns the number of points in the first linestring in the geometry field in a num_points attribute on each element of the GeoQuerySet; otherwise sets with None.
Spatial Aggregates¶
Aggregate Methods¶
Deprecated since version 1.8: Aggregate methods are now deprecated. Prefer using their function-based equivalents.
collect¶
- GeoQuerySet.collect(**kwargs)¶
Deprecated since version 1.8: Use the Collect aggregate instead.
Shortcut for aggregate(Collect(<field>)).
extent¶
- GeoQuerySet.extent(**kwargs)¶
Deprecated since version 1.8: Use the Extent aggregate instead.
Shortcut for aggregate(Extent(<field>)).
extent3d¶
- GeoQuerySet.extent3d(**kwargs)¶
Deprecated since version 1.8: Use the Extent aggregate instead.
Shortcut for aggregate(Extent3D(<field>)).
Aggregate Functions¶
Django provides some GIS-specific aggregate functions. For details on how to use these aggregate functions, see the topic guide on aggregation.
Keyword Argument | Description |
---|---|
tolerance | This keyword is for Oracle only. It is for the tolerance value used by the SDOAGGRTYPE procedure; the Oracle documentation has more details. |
Example:
>>> from django.contrib.gis.db.models import Extent, Union
>>> WorldBorder.objects.aggregate(Extent('mpoly'), Union('mpoly'))
Collect¶
- class Collect(geo_field)¶
Availability: PostGIS, Spatialite (≥3.0)
Returns a GEOMETRYCOLLECTION or a MULTI geometry object from the geometry column. This is analogous to a simplified version of the Union aggregate, except it can be several orders of magnitude faster than performing a union because it simply rolls up geometries into a collection or multi object, not caring about dissolving boundaries.
Extent¶
- class Extent(geo_field)¶
Availability: PostGIS, Oracle, Spatialite (≥3.0)
Returns the extent of all geo_field in the QuerySet as a four-tuple, comprising the lower left coordinate and the upper right coordinate.
Example:
>>> qs = City.objects.filter(name__in=('Houston', 'Dallas')).aggregate(Extent('poly'))
>>> print(qs[poly__extent])
(-96.8016128540039, 29.7633724212646, -95.3631439208984, 32.782058715820)
Extent3D¶
- class Extent3D(geo_field)¶
Availability: PostGIS
Returns the 3D extent of all geo_field in the QuerySet as a six-tuple, comprising the lower left coordinate and upper right coordinate (each with x, y, and z coordinates).
Example:
>>> qs = City.objects.filter(name__in=('Houston', 'Dallas')).aggregate(Extent3D('poly'))
>>> print(qs[poly__extent3d])
(-96.8016128540039, 29.7633724212646, 0, -95.3631439208984, 32.782058715820, 0)
MakeLine¶
- class MakeLine(geo_field)¶
Availability: PostGIS
Returns a LineString constructed from the point field geometries in the QuerySet. Currently, ordering the queryset has no effect.
Example:
>>> print(City.objects.filter(name__in=('Houston', 'Dallas')
... ).aggregate(MakeLine('poly'))[poly__makeline]
LINESTRING (-95.3631510000000020 29.7633739999999989, -96.8016109999999941 32.7820570000000018)
Union¶
- class Union(geo_field)¶
Availability: PostGIS, Oracle, SpatiaLite
This method returns a GEOSGeometry object comprising the union of every geometry in the queryset. Please note that use of Union is processor intensive and may take a significant amount of time on large querysets.
Note
If the computation time for using this method is too expensive, consider using Collect instead.
Example:
>>> u = Zipcode.objects.aggregate(Union(poly)) # This may take a long time.
>>> u = Zipcode.objects.filter(poly__within=bbox).aggregate(Union(poly)) # A more sensible approach.
Footnotes
[1] | See OpenGIS Simple Feature Specification For SQL, at Ch. 2.1.13.2, p. 2-13 (The Dimensionally Extended Nine-Intersection Model). |
[2] | See SDO_RELATE documentation, from Ch. 11 of the Oracle Spatial User’s Guide and Manual. |
[3] | (1, 2) For an explanation of this routine, read Quirks of the “Contains” Spatial Predicate by Martin Davis (a PostGIS developer). |
[4] | Refer to the PostGIS ST_ContainsProperly documentation for more details. |