.. _ref-geoquerysets: ========================= GeoQuerySet API Reference ========================= .. currentmodule:: django.contrib.gis.db.models .. class:: GeoQuerySet([model=None]) .. _spatial-lookups: Spatial Lookups =============== Just like when using the :ref:`queryset-api`, interaction with ``GeoQuerySet`` by :ref:`chaining filters `. Instead of the regular Django :ref:`field-lookups`, the spatial lookups in this section are available for :class:`GeometryField`. For an introduction, see the :ref:`spatial lookups introduction `. For an overview of what lookups are compatible with a particular spatial backend, refer to the :ref:`spatial lookup compatibility table `. .. fieldlookup:: bbcontains 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)`` ========== ========================== .. fieldlookup:: bboverlaps 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)`` ========== ========================== .. fieldlookup:: contained 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)`` ========== ========================== .. fieldlookup:: gis-contains 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)`` ========== ============================ .. fieldlookup:: contains_properly contains_properly ----------------- .. versionadded:: 1.2 *Availability*: PostGIS Returns true if the lookup geometry intersects the interior of the geometry field, but not the boundary (or exterior). [#fncontainsproperly]_ .. note:: Requires PostGIS 1.4 and above. Example:: Zipcode.objects.filter(poly__contains_properly=geom) ========== =================================== Backend SQL Equivalent ========== =================================== PostGIS ``ST_ContainsProperly(poly, geom)`` ========== =================================== .. fieldlookup:: coveredby coveredby --------- *Availability*: PostGIS, Oracle Tests if no point in the geometry field is outside the lookup geometry. [#fncovers]_ Example:: Zipcode.objects.filter(poly__coveredby=geom) ========== ============================= Backend SQL Equivalent ========== ============================= PostGIS ``ST_CoveredBy(poly, geom)`` Oracle ``SDO_COVEREDBY(poly, geom)`` ========== ============================= .. fieldlookup:: covers covers ------ *Availability*: PostGIS, Oracle Tests if no point in the lookup geometry is outside the geometry field. [#fncovers]_ Example:: Zipcode.objects.filter(poly__covers=geom) ========== ========================== Backend SQL Equivalent ========== ========================== PostGIS ``ST_Covers(poly, geom)`` Oracle ``SDO_COVERS(poly, geom)`` ========== ========================== .. fieldlookup:: crosses 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)`` ========== ========================== .. fieldlookup:: disjoint 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 .. fieldlookup:: exact .. fieldlookup:: same_as exact, same_as -------------- *Availability*: PostGIS, Oracle, MySQL, SpatiaLite .. fieldlookup:: intersects 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)`` ========== ================================================= .. fieldlookup:: overlaps overlaps -------- *Availability*: PostGIS, Oracle, MySQL, SpatiaLite .. fieldlookup:: relate 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. [#fnde9im]_ 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 compreised 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'``. [#fnsdorelate]_ The relation strings are case-insensitive. Example:: Zipcode.objects.filter(poly__relate(geom, 'anyinteract')) Oracle SQL equivalent:: SELECT ... WHERE SDO_RELATE(poly, geom, 'anyinteract') .. fieldlookup:: touches 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)`` ========== ========================== .. fieldlookup:: within 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)`` ========== ========================== .. fieldlookup:: left 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 .. fieldlookup:: right 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 .. fieldlookup:: overlaps_left 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 .. fieldlookup:: overlaps_right 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 .. fieldlookup:: overlaps_above 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 .. fieldlookup:: overlaps_below 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 .. fieldlookup:: strictly_above 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 .. fieldlookup:: strictly_below strictly_below -------------- *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 .. _distance-lookups: Distance Lookups ================ *Availability*: PostGIS, Oracle, SpatiaLite For an overview on performing distance queries, please refer to the :ref:`distance queries introduction `. Distance lookups take the following form:: __=(, [, '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 :class:`~django.contrib.gis.measure.Distance` object). On every distance lookup but :lookup:`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``). .. fieldlookup:: distance_gt 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`` ========== =============================================== .. fieldlookup:: distance_gte 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`` ========== ================================================ .. fieldlookup:: distance_lt 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`` ========== =============================================== .. fieldlookup:: distance_lte 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`` ========== ================================================ .. fieldlookup:: dwithin dwithin ------- Returns models where the distance to the geometry field from the lookup geometry are within the given distance from one another. 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. .. fieldlookup:: equals ``GeoQuerySet`` Methods ======================= ``GeoQuerySet`` methods specify that a spatial operation be performed on each patial 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 :ref:`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`` ~~~~~~~~ .. method:: GeoQuerySet.area(**kwargs) Returns the area of the geographic field in an ``area`` attribute on each element of this GeoQuerySet. ``distance`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.distance(geom, **kwargs) 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 :class:`~django.contrib.gis.measure.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 :class:`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 :class:`~django.contrib.gis.measure.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 the :ref:`ref-measure` for usage details and the list of :ref:`supported_units`. __ http://code.djangoproject.com/browser/django/trunk/django/contrib/gis/tests/distapp/models.py __ http://en.wikipedia.org/wiki/Tasmania ``length`` ~~~~~~~~~~ .. method:: GeoQuerySet.length(**kwargs) Returns the length of the geometry field in a ``length`` attribute (a :class:`~django.contrib.gis.measure.Distance` object) on each model in the queryset. ``perimeter`` ~~~~~~~~~~~~~ .. method:: GeoQuerySet.perimeter(**kwargs) Returns the perimeter of the geometry field in a ``perimeter`` attribute (a :class:`~django.contrib.gis.measure.Distance` object) on each model in the queryset. Geometry Relationships ---------------------- The following methods take no arguments, and attach geometry objects each element of the :class:`GeoQuerySet` that is the result of relationship function evaluated on the geometry field. ``centroid`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.centroid(**kwargs) *Availability*: PostGIS, Oracle, SpatiaLite Returns the ``centroid`` value for the geographic field in a ``centroid`` attribute on each element of the ``GeoQuerySet``. ``envelope`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.envelope(**kwargs) *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`` ~~~~~~~~~~~~~~~~~~~~ .. method:: GeoQuerySet.point_on_surface(**kwargs) *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`` ~~~~~~~~~~~~~ .. method:: GeoQuerySet.force_rhr(**kwargs) .. versionadded:: 1.2 *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`` ~~~~~~~~~~~~~~~~ .. method:: GeoQuerySet.reverse_geom(**kwargs) .. versionadded:: 1.2 *Availability*: PostGIS, Oracle Reverse the coordinate order of the geometry field, and attaches as a ``reverse`` attribute on each element of the queryset. ``scale`` ~~~~~~~~~ .. method:: GeoQuerySet.scale(x, y, z=0.0, **kwargs) *Availability*: PostGIS, SpatiaLite ``snap_to_grid`` ~~~~~~~~~~~~~~~~ .. method:: GeoQuerySet.snap_to_grid(*args, **kwargs) 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`` ~~~~~~~~~~~~~ .. method:: GeoQuerySet.transform(srid=4326, **kwargs) *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 ... ``translate`` ~~~~~~~~~~~~~ .. method:: GeoQuerySet.translate(x, y, z=0.0, **kwargs) *Availability*: PostGIS, SpatiaLite Translates the geometry field to a new location using the given numeric parameters as offsets. 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`` ~~~~~~~~~~~~~~ .. method:: GeoQuerySet.difference(geom) Returns the spatial difference of the geographic field with the given geometry in a ``difference`` attribute on each element of the ``GeoQuerySet``. ``intersection`` ~~~~~~~~~~~~~~~~ .. method:: GeoQuerySet.intersection(geom) Returns the spatial intersection of the geographic field with the given geometry in an ``intersection`` attribute on each element of the ``GeoQuerySet``. ``sym_difference`` ~~~~~~~~~~~~~~~~~~ .. method:: GeoQuerySet.sym_difference(geom) Returns the symmetric difference of the geographic field with the given geometry in a ``sym_difference`` attribute on each element of the ``GeoQuerySet``. ``union`` ~~~~~~~~~ .. method:: GeoQuerySet.union(geom) Returns the union of the geographic field with the given geometry in an ``union`` 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`` ~~~~~~~~~~~ .. method:: GeoQuerySet.geohash(preceision=20, **kwargs) .. versionadded:: 1.2 Attaches a ``geohash`` attribute to every model the queryset containing the `GeoHash`__ representation of the geometry. __ http://geohash.org/ ``geojson`` ~~~~~~~~~~~ .. method:: GeoQuerySet.geojson(**kwargs) *Availability*: PostGIS 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. ===================== ===================================================== __ http://geojson.org/ ``gml`` ~~~~~~~ .. method:: GeoQuerySet.gml(**kwargs) *Availability*: PostGIS, Oracle 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 -147.78711,70.245363 ... -147.78711,70.245363 ===================== ===================================================== 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. ===================== ===================================================== __ http://en.wikipedia.org/wiki/Geography_Markup_Language ``kml`` ~~~~~~~ .. method:: GeoQuerySet.kml(**kwargs) *Availability*: PostGIS 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 -103.04135,36.217596,0 ... -103.04135,36.217596,0 ===================== ===================================================== 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. ===================== ===================================================== __ http://code.google.com/apis/kml/documentation/ ``svg`` ~~~~~~~ .. method:: GeoQuerySet.svg(**kwargs) *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. ===================== ===================================================== __ http://www.w3.org/Graphics/SVG/ Miscellaneous ------------- ``mem_size`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.mem_size(**kwargs) *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`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.num_geom(**kwargs) *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`` ~~~~~~~~~~~~~~ .. method:: GeoQuerySet.num_points(**kwargs) *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 ----------------- ``collect`` ~~~~~~~~~~~ .. method:: GeoQuerySet.collect(**kwargs) *Availability*: PostGIS Returns a ``GEOMETRYCOLLECTION`` or a ``MULTI`` geometry object from the geometry column. This is analagous to a simplified version of the :meth:`GeoQuerySet.unionagg` method, except it can be several orders of magnitude faster than peforming a union because it simply rolls up geometries into a collection or multi object, not caring about dissolving boundaries. ``extent`` ~~~~~~~~~~ .. method:: GeoQuerySet.extent(**kwargs) *Availability*: PostGIS, Oracle Returns the extent of the ``GeoQuerySet`` as a four-tuple, comprising the lower left coordinate and the upper right coordinate. Example:: >>> qs = City.objects.filter(name__in=('Houston', 'Dallas')) >>> print qs.extent() (-96.8016128540039, 29.7633724212646, -95.3631439208984, 32.782058715820) ``extent3d`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.extent3d(**kwargs) .. versionadded:: 1.2 *Availability*: PostGIS Returns the 3D extent of the ``GeoQuerySet`` as a six-tuple, comprising the lower left coordinate and upper right coordinate. Example:: >>> qs = City.objects.filter(name__in=('Houston', 'Dallas')) >>> print qs.extent3d() (-96.8016128540039, 29.7633724212646, 0, -95.3631439208984, 32.782058715820, 0) ``make_line`` ~~~~~~~~~~~~~ .. method:: GeoQuerySet.make_line(**kwargs) *Availability*: PostGIS Returns a ``LineString`` constructed from the point field geometries in the ``GeoQuerySet``. Currently, ordering the queryset has no effect. Example:: >>> print City.objects.filter(name__in=('Houston', 'Dallas')).make_line() LINESTRING (-95.3631510000000020 29.7633739999999989, -96.8016109999999941 32.7820570000000018) ``unionagg`` ~~~~~~~~~~~~ .. method:: GeoQuerySet.unionagg(**kwargs) *Availability*: PostGIS, Oracle, SpatiaLite This method returns a :class:`~django.contrib.gis.geos.GEOSGeometry` object comprising the union of every geometry in the queryset. Please note that use of ``unionagg`` 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 :meth:`GeoQuerySet.collect` instead. Example:: >>> u = Zipcode.objects.unionagg() # This may take a long time. >>> u = Zipcode.objects.filter(poly__within=bbox).unionagg() # A more sensible approach. ===================== ===================================================== 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. ===================== ===================================================== __ http://download.oracle.com/docs/html/B14255_01/sdo_intro.htm#sthref150 Aggregate Functions ------------------- Example:: >>> from django.contrib.gis.db.models import Extent, Union >>> WorldBorders.objects.aggregate(Extent('mpoly'), Union('mpoly')) ``Collect`` ~~~~~~~~~~~ .. class:: Collect(geo_field) Returns the same as the :meth:`GeoQuerySet.collect` aggregate method. ``Extent`` ~~~~~~~~~~ .. class:: Extent(geo_field) Returns the same as the :meth:`GeoQuerySet.extent` aggregate method. ``Extent3D`` ~~~~~~~~~~~~ .. class:: Extent3D(geo_field) .. versionadded:: 1.2 Returns the same as the :meth:`GeoQuerySet.extent3d` aggregate method. ``MakeLine`` ~~~~~~~~~~~~ .. class:: MakeLine(geo_field) Returns the same as the :meth:`GeoQuerySet.make_line` aggregate method. ``Union`` ~~~~~~~~~ .. class:: Union(geo_field) Returns the same as the :meth:`GeoQuerySet.union` aggregate method. .. rubric:: Footnotes .. [#fnde9im] *See* `OpenGIS Simple Feature Specification For SQL `_, at Ch. 2.1.13.2, p. 2-13 (The Dimensionally Extended Nine-Intersection Model). .. [#fnsdorelate] *See* `SDO_RELATE documentation `_, from Ch. 11 of the Oracle Spatial User's Guide and Manual. .. [#fncovers] For an explanation of this routine, read `Quirks of the "Contains" Spatial Predicate `_ by Martin Davis (a PostGIS developer). .. [#fncontainsproperly] Refer to the PostGIS ``ST_ContainsProperly`` `documentation `_ for more details.