Fungsi Basisdata Geografis¶

Area¶

class Area(expression, **extra)¶

Tersedia: MySQL, Oracle, PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns the area of the field as an Area measure.

MySQL and SpatiaLite without LWGEOM don't support area calculations on geographic SRSes.

AsGeoJSON¶

class AsGeoJSON(expression, bbox=False, crs=False, precision=8, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a 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 Penserial GeoJSON.

Contoh:

>>> City.objects.annotate(json=AsGeoJSON('point')).get(name='Chicago').json
{"type":"Point","coordinates":[-87.65018,41.85039]}

AsGML¶

class AsGML(expression, version=2, precision=8, **extra)¶

Tersedia: Oracle, PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a Geographic Markup Language (GML) representation of the geometry.

Contoh:

>>> qs = Zipcode.objects.annotate(gml=AsGML('poly'))
>>> print(qs[0].gml)
<gml:Polygon srsName="EPSG:4326"><gml:OuterBoundaryIs>-147.78711,70.245363 ...
-147.78711,70.245363</gml:OuterBoundaryIs></gml:Polygon>

AsKML¶

class AsKML(expression, precision=8, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a Keyhole Markup Language (KML) representation of the geometry.

Contoh:

>>> qs = Zipcode.objects.annotate(kml=AsKML('poly'))
>>> print(qs[0].kml)
<Polygon><outerBoundaryIs><LinearRing><coordinates>-103.04135,36.217596,0 ...
-103.04135,36.217596,0</coordinates></LinearRing></outerBoundaryIs></Polygon>

AsSVG¶

class AsSVG(expression, relative=False, precision=8, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a Scalable Vector Graphics (SVG) representation of the geometry.

BoundingCircle¶

class BoundingCircle(expression, num_seg=48, **extra)¶

Tersedia: PostGIS, Oracle (≥ 12.1.0.2)

Accepts a single geographic field or expression and returns the smallest circle polygon that can fully contain the geometry.

Parameter num_seg hanya digunakan pada PostGIS.

Centroid¶

class Centroid(expression, **extra)¶

Tersedia: MySQL, PostGIS, Oracle, SpatiaLite

Menerima bidang geografis tunggal atau mengembalikan nilai centroid dari geometri.

Difference¶

class Difference(expr1, expr2, **extra)¶

Tersedia: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Menerima dua bidang geografis atau pernyataan dan mengembalikan perbedaan geometri, yaitu bagian dari geometri A yang tidak berinteraksi dengan geometri B.

Distance¶

class Distance(expr1, expr2, spheroid=None, **extra)¶

Tersedia: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the distance between them, as a Distance object. On MySQL, a raw float value is returned when the coordinates are geodetic.

On backends that support distance calculation on geodetic coordinates, the proper backend function is automatically chosen depending on the SRID value of the geometries (e.g. ST_DistanceSphere on PostGIS).

Ketika jarak dihitung dengan kordinat (bersiku-siku) geodetic, seperti halnya dengan awalan SRID WGS84 (4326), anda dapat menyetel argumen kata kunci spheroid untuk memutuskan jika perhitungan harus berdasarkan pada bulatan sederhana (kurang akurat, kurang sumber daya-intensif) atau pada sebuah berbentuk bola (lebih akurat, lebih sumber daya-intensif)

In the following example, the distance from the city of Hobart to every other PointField in the AustraliaCity queryset is calculated:

>>> from django.contrib.gis.db.models.functions import Distance
>>> pnt = AustraliaCity.objects.get(name='Hobart').point
>>> for city in AustraliaCity.objects.annotate(distance=Distance('point', pnt)):
...     print(city.name, city.distance)
Wollongong 990071.220408 m
Shellharbour 972804.613941 m
Thirroul 1002334.36351 m
...

Envelope¶

class Envelope(expression, **extra)¶

Tersedia: MySQL, PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns the geometry representing the bounding box of the geometry.

ForceRHR¶

class ForceRHR(expression, **extra)¶

Tersedia: PostGIS

Accepts a single geographic field or expression and returns a modified version of the polygon/multipolygon in which all of the vertices follow the right-hand rule.

GeoHash¶

class GeoHash(expression, precision=None, **extra)¶

Tersedia: PostGIS, SpatiaLite (LWGEOM)

Menerima bidang geografi tunggal atau pernyataan dan mengembalikan perwakilan GeoHash dari geometri.

Argumen kata kunci precision mengendalikan sejumlah karakter dalam hasilnya.

Intersection¶

class Intersection(expr1, expr2, **extra)¶

Tersedia: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Menerima dua bidang geografi dan pernyataan dan mengembalikan persimpangan geometri diantara mereka.

IsValid¶

class IsValid(expr)¶

Tersedia: PostGIS, Oracle, SpatiaLite (LWGEOM)

Menerima sebuah bidang geografi atau pernyataan dan percobaan jika nilai berbentuk bagus. Mengembalikan True jika nilainya adalah geometri sah dan False sebaliknya.

Length¶

class Length(expression, spheroid=True, **extra)¶

Tersedia: MySQL, Oracle, PostGIS, SpatiaLite

Accepts a single geographic linestring or multilinestring field or expression and returns its length as a Distance measure.

On PostGIS and SpatiaLite, when the coordinates are geodetic (angular), you can specify if the calculation should be based on a simple sphere (less accurate, less resource-intensive) or on a spheroid (more accurate, more resource-intensive) with the spheroid keyword argument.

MySQL tidak mendukung dukungan perhitungan panjang pada geografis SRS.

MakeValid¶

class MakeValid(expr)¶

Tersedia: PostGIS, SpatiaLite (LWGEOM)

Accepts a geographic field or expression and attempts to convert the value into a valid geometry without losing any of the input vertices. Geometries that are already valid are returned without changes. Simple polygons might become a multipolygon and the result might be of lower dimension than the input.

MemSize¶

class MemSize(expression, **extra)¶

Tersedia: PostGIS

Accepts a single geographic field or expression and returns the memory size (number of bytes) that the geometry field takes.

NumGeometries¶

class NumGeometries(expression, **extra)¶

Tersedia: MySQL, PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the number of geometries if the geometry field is a collection (e.g., a GEOMETRYCOLLECTION or MULTI* field). Returns 1 for single geometries.

Pada MySQL, mengembalikan None untuk geometri tunggal.

NumPoints¶

class NumPoints(expression, **extra)¶

Tersedia: MySQL, PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the number of points in the first linestring in the geometry field; otherwise returns None.

Perimeter¶

class Perimeter(expression, **extra)¶

Tersedia: PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns the perimeter of the geometry field as a Distance object.

PointOnSurface¶

class PointOnSurface(expression, **extra)¶

Tersedia: PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns a Point geometry guaranteed to lie on the surface of the field; otherwise returns None.

Reverse¶

class Reverse(expression, **extra)¶

Tersedia: PostGIS, Oracle, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with reversed coordinates.

Scale¶

class Scale(expression, x, y, z=0.0, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with scaled coordinates by multiplying them with the x, y, and optionally z parameters.

SnapToGrid¶

class SnapToGrid(expression, *args, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with all points snapped to the given grid. How the geometry is snapped to the grid depends on how many numeric (either float, integer, or long) arguments are given.

SymDifference¶

class SymDifference(expr1, expr2, **extra)¶

Tersedia: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Accepts two geographic fields or expressions and returns the geometric symmetric difference (union without the intersection) between the given parameters.

Transform¶

class Transform(expression, srid, **extra)¶

Tersedia: PostGIS, Oracle, SpatiaLite

Accepts a geographic field or expression and a SRID integer code, and returns the transformed geometry to the spatial reference system specified by the srid parameter.

Translate¶

class Translate(expression, x, y, z=0.0, **extra)¶

Tersedia: PostGIS, SpatiaLite

Accepts a single geographic field or expression and returns a geometry with its coordinates offset by the x, y, and optionally z numeric parameters.

Union¶

class Union(expr1, expr2, **extra)¶

Tersedia: MySQL (≥ 5.6.1), PostGIS, Oracle, SpatiaLite

Menerima dua bidang geografi atau pernyataan dan mengembalikan gabungan dari kedua geometri.