API GDALLink to this heading#

Data ContohLink to this heading#

The GDAL/OGR tools described here are designed to help you read in your geospatial data, in order for most of them to be useful you have to have some data to work with. If you're starting out and don't yet have any data of your own to use, GeoDjango tests contain a number of simple data sets that you can use for testing. You can download them here:

$ wget https://raw.githubusercontent.com/django/django/master/tests/gis_tests/data/cities/cities.{shp,prj,shx,dbf}
$ wget https://raw.githubusercontent.com/django/django/master/tests/gis_tests/data/rasters/raster.tif

DataSourceLink to this heading#

DataSource adalah sebuah pembungkus untuk obyek sumber data OGR yang mendukung membaca data dari beragam dari bentuk berkas geospasial didukung-OGR dan sumber data menggunakan sederhana, konsisten antarmuka. Setiap sumber data diwakili oleh sebuah obyek DataSource yang mengandung satu atau lebih lapisan data. Setiap lapisan, diwakili oleh Layer object, mengandung beberapa nomor dari fitur-fitur geografik (Feature), informasi tentang jenis dari fitur-fitur mengandung di lapisan itu (sebagai contoh titik, poligon, dll.), sama halnya nama-nama dan jenis-jenis dari bidang tambahan apapun (Field) dari data yang mungkin terhubung dengan setiap fitur di lapisan itu.

class DataSource(ds_input, encoding='utf-8')Link to this definition#

Pembangun untuk DataSource hanya membutuhkan satu parameter: jalur dari berkas anda ingin baca. Bagaimanapun, OGR juga mendukung beragam sumber data lebih rumit, termasuk basisdata, yang mungkin diakses dengan melewatkan string nama khusus daripada jalur. Untuk informasi lebih, lihat dokumentasi OGR Vector Formats. Sifat name dari sebuah instance DataSource memberikan nama OGR dari sumber data pokok yang itu sedang gunakan.

Pilihan parameter encoding mengizinkan anda menentukan penyandian bukan-standar dari string di sumber. Ini khususnya berguna ketika anda mendapatkan pengecualian DjangoUnicodeDecodeError selagi membaca nilai bidang.

Sekali anda telah membuat DataSource anda, anda dapat menemukan seberapa banyak lapisan data itu kandung dengan mengakses sifat layer_count, atau (setara) dengan menggunakan fungsi len(). Untuk informasi pada mengakses lapisan dari data mereka sendiri, lihat bagian lain:

Code

>>> from django.contrib.gis.gdal import DataSource
>>> ds = DataSource('/path/to/your/cities.shp')
>>> ds.name
'/path/to/your/cities.shp'
>>> ds.layer_count                  # This file only contains one layer
1

layer_countLink to this definition#

Mengembalikan sejumlah lapisan di sumber data.

nameLink to this definition#

Mengembalikan nama dari sumber data.

LapisanLink to this heading#

class LayerLink to this definition#

Layer adalah sebuah pembungkus untuk lapisan dari data di obyek DataSource. Anda tidak pernah membuat obyek Layer secara langsung. Sebagai gantinya, anda mengambil mereka dari obyek DataSource, yang pada dasarnya wadah standar Python dari obyek Layer. Sebagai contoh, anda dapat mengakses lapisan khusus dengan indeksnya (sebagai contoh ds[0] untuk mengakses lapisan pertama), atau anda dapat mengulang terhadap semua lapisan di wadah dalam perulangan loop. Layer itu sendiri bertindak sebagai sebuah wadah untuk fitur-fitur geometris.

Khususnya, semua fitur di lapisan yang diberikan mempunyai jenis geometri sama. Sifat geom_type dari lapisan adalah sebuah OGRGeomType yang mencirikan jenis fitur. Kami dapat menggunakan itu untuk mencetak beberapa informasi dasar tentang setiap lapisan di DataSource:

Code

>>> for layer in ds:
...     print('Layer "%s": %i %ss' % (layer.name, len(layer), layer.geom_type.name))
...
Layer "cities": 3 Points

Keluaran contoh adalah dari sumber data kota, dimuat diatas, yang ternyata mengandung satu lapisan, dipanggil "cities", yang mengandung tida titik fitur. Untuk kemudahan, contoh-contoh diatas menganggap bahwa anda telah menyimpan lapisan itu di variabel layer:

Code

>>> layer = ds[0]

nameLink to this definition#

Mengembalikan nama lapisan ini di sumber data.

Code

>>> layer.name
'cities'

num_featLink to this definition#

Mengembalikan sejumlah fitur-fitur di lapisan. Sama seperti len(layer):

Code

>>> layer.num_feat
3

geom_typeLink to this definition#

Mengembalikan jenis geometri dari lapisan, sebagai sebuah obyek OGRGeomType:

Code

>>> layer.geom_type.name
'Point'

num_fieldsLink to this definition#

Mengembalikan sejumlah bidang di lapisan, yaitu sejumlah bidang dari data terhubung dengan setiap fitur di lapisan:

Code

>>> layer.num_fields
4

fieldsLink to this definition#

Mengembalikan daftar nama dari setiap bidang di lapisan ini:

Code

>>> layer.fields
['Name', 'Population', 'Density', 'Created']

Mengembalikan daftar dari jenis-jenis data dari setiap bidang di lapisan ini. Ini adalah subkelas dari Field, diobrolkan dibawah:

Code

>>> [ft.__name__ for ft in layer.field_types]
['OFTString', 'OFTReal', 'OFTReal', 'OFTDate']

field_widthsLink to this definition#

Mengembalikan daftar dari bidang maksimal untuk setiap bidang dalam lapisan ini:

Code

>>> layer.field_widths
[80, 11, 24, 10]

field_precisionsLink to this definition#

Mengembalikan daftar dari angka ketelitian untuk setiap dari bidang-bidang dalam lapisan ini. Ini tidak berarti (dan disetel ke nol) untuk bidang bukan-numerik:

Code

>>> layer.field_precisions
[0, 0, 15, 0]

extentLink to this definition#

Mengembalikan tingkatan spasial dari lapisan ini, sebagai sebuah obyek Envelope:

Code

>>> layer.extent.tuple
(-104.609252, 29.763374, -95.23506, 38.971823)

srsLink to this definition#

Sifat yang mengembalikan SpatialReference terkait dengan lapisan ini:

Code

>>> print(layer.srs)
GEOGCS["GCS_WGS_1984",
    DATUM["WGS_1984",
        SPHEROID["WGS_1984",6378137,298.257223563]],
    PRIMEM["Greenwich",0],
    UNIT["Degree",0.017453292519943295]]

Jika Layer tidak mempunyai informasi acuan spasial terkait dengan itu, `` None`` dikembalikan.

spatial_filterLink to this definition#

Property that may be used to retrieve or set a spatial filter for this layer. A spatial filter can only be set with an OGRGeometry instance, a 4-tuple extent, or None. When set with something other than None, only features that intersect the filter will be returned when iterating over the layer:

Code

>>> print(layer.spatial_filter)
None
>>> print(len(layer))
3
>>> [feat.get('Name') for feat in layer]
['Pueblo', 'Lawrence', 'Houston']
>>> ks_extent = (-102.051, 36.99, -94.59, 40.00) # Extent for state of Kansas
>>> layer.spatial_filter = ks_extent
>>> len(layer)
1
>>> [feat.get('Name') for feat in layer]
['Lawrence']
>>> layer.spatial_filter = None
>>> len(layer)
3

get_fields()Link to this definition#

Sebuah metode yang mengembalikan sebuah daftar dari nilai-nilai dari bidang yang diberikan untuk setiap fitur dalam lapisan:

Code

>>> layer.get_fields('Name')
['Pueblo', 'Lawrence', 'Houston']

get_geoms(geos=False)Link to this definition#

A method that returns a list containing the geometry of each feature in the layer. If the optional argument geos is set to True then the geometries are converted to GEOSGeometry objects. Otherwise, they are returned as OGRGeometry objects:

Code

>>> [pt.tuple for pt in layer.get_geoms()]
[(-104.609252, 38.255001), (-95.23506, 38.971823), (-95.363151, 29.763374)]

test_capability(capability)Link to this definition#

Returns a boolean indicating whether this layer supports the given capability (a string). Examples of valid capability strings include: 'RandomRead', 'SequentialWrite', 'RandomWrite', 'FastSpatialFilter', 'FastFeatureCount', 'FastGetExtent', 'CreateField', 'Transactions', 'DeleteFeature', and 'FastSetNextByIndex'.

FeatureLink to this heading#

class FeatureLink to this definition#

Feature membungkus fitur OGR. Anda tidak pernah membuat obyek Feature secara langsung. Sebagai gantinya, anda mengambil mereka dari obyek Layer. Setiap fitur terdiri dari sebuah geometri dan sekumpulan bidang mengandung sifat-sifat tambahan. Geometri dari sebuah bidang adalah dapat diakses melalui sifat geom nya, yang mengembalikan sebuah obyek OGRGeometry. Sebuah Feature berperilaku seperti wadah Python standar untuk bidangnya, yang itu dikembalikan sebagai obyek Field: anda dapat mengakses sebuah bidang secara langsung berdasarkan indeks atau namanya, atau dapat berulang terhadap bidang-bidang fitur, sebagai contoh di sebuah perulangan for.

geomLink to this definition#

Mengembalikan geometri untuk fotur ini, sebagai sebuah obyek OGRGeometry:

Code

>>> city.geom.tuple
(-104.609252, 38.255001)

getLink to this definition#

Sebuah metode yang mengembalikan nilai dari bidang yang diberikan (ditentukan oleh nama) untuk fitur ini, bukan sebuah obyek pembungkus Field:

Code

>>> city.get('Population')
102121

geom_typeLink to this definition#

Returns the type of geometry for this feature, as an OGRGeomType object. This will be the same for all features in a given layer and is equivalent to the Layer.geom_type property of the Layer object the feature came from.

num_fieldsLink to this definition#

Returns the number of fields of data associated with the feature. This will be the same for all features in a given layer and is equivalent to the Layer.num_fields property of the Layer object the feature came from.

fieldsLink to this definition#

Returns a list of the names of the fields of data associated with the feature. This will be the same for all features in a given layer and is equivalent to the Layer.fields property of the Layer object the feature came from.

fidLink to this definition#

Mengembalikan penciri fitur dalam lapisan:

Code

>>> city.fid
0

layer_nameLink to this definition#

Mengembalikan nama dari Layer yang berasal fitur. Ini akan menjadi sama untuk semua fitur dalam lapisan yang diberikan:

Code

>>> city.layer_name
'cities'

indexLink to this definition#

Sebuah metode yang mengembalikan indeks dari nama bidang yang diberikan. Ini akan sama untuk semua fitur-fitur dalam lapisan yang diberikan:

Code

>>> city.index('Population')
1

FieldLink to this heading#

class FieldLink to this definition#

nameLink to this definition#

Mengembalikan nama dari bidang ini:

Code

>>> city['Name'].name
'Name'

typeLink to this definition#

Mengembalikan jenis OGR dari bidang ini, sebagai sebuah integer. Dictionary FIELD_CLASSES memetakan nilai-nilai ini kedalam subkelas dari Field:

Code

>>> city['Density'].type
2

type_nameLink to this definition#

Mengembalikan string dengan nama dari jenis data dari bidang ini:

Code

>>> city['Name'].type_name
'String'

valueLink to this definition#

Mengembalikan nilai dari bidang ini. Kelas Field itu sendiri mengembalikan nilai sebagai sebuah string, tetapi setiap subkelas mengembalikan nilai dalam bentuk paling sesuai:

Code

>>> city['Population'].value
102121

widthLink to this definition#

Mengembalikan lebar bidang ini:

Code

>>> city['Name'].width
80

precisionLink to this definition#

Mengembalikan ketelitian numerik dari bidang ini. Ini tidak berarti (dan disetel ke nol) untuk bidang-bidang bukan-numerik:

Code

>>> city['Density'].precision
15

as_double()Link to this definition#

Mengembalikan nilai dari bidang sebagai double (float):

Code

>>> city['Density'].as_double()
874.7

as_int()Link to this definition#

Mengembalikan nilai dari bidang sebagai integer:

Code

>>> city['Population'].as_int()
102121

as_string()Link to this definition#

Mengembalikan nilai dari bidang sebagai deretan kalimat:

Code

>>> city['Name'].as_string()
'Pueblo'

as_datetime()Link to this definition#

Mengembalikan nilai dari bidang sebagai tuple dari komponen tanggal dan waktu:

Code

>>> city['Created'].as_datetime()
(c_long(1999), c_long(5), c_long(23), c_long(0), c_long(0), c_long(0), c_long(0))

DriverLink to this heading#

class Driver(dr_input)Link to this definition#

Kelas Driver digunakan secara mendalam untuk membungkus sebuah driver DataSource OGR.

driver_countLink to this definition#

Mengembalikan sejumlah driver vektor OGR saat ini terdaftar.

OGRGeometryLink to this heading#

Obyek-obyek OGRGeometry berbagi fungsi mirip dengan obyek GEOSGeometry dan pembungkus tipis disekitar perwakilan geometri internal OGR. Dengan demikian, mereka mengizinkan untuk lebih efektid mengakses ke data ketika menggunakan DataSource. Tidak seprti pasangan GEOS nya, OGRGeometry mendukung sistem acuan spasial dan perubahan kordinat:

>>> from django.contrib.gis.gdal import OGRGeometry
>>> polygon = OGRGeometry('POLYGON((0 0, 5 0, 5 5, 0 5))')

class OGRGeometry(geom_input, srs=None)Link to this definition#

Obyek ini adalah sebuah pembungkus untuk kelas OGR Geometry. Obyek-obyek ini diinstasiasikan secara langsung dari parameter geom_input yang diberikan, yang mungkin berupa string mengandung WKT, HEX, GeoJSON, sebuah buffer mengandung data WKB, atau sebuah obyek OGRGeomType. Obyek-obyek ini juga dikembalikan dari atribut Feature.geom, ketika membaca data vektor dari Layer (yaitu pada giliran bagian dari sebuah DataSource).

classmethod from_gml(gml_string)Link to this definition#

Membangun sebuah OGRGeometry dari string GML yang diberikan.

classmethod from_bbox(bbox)Link to this definition#

Membangun sebuah Polygon dari kotak-terikat diberikan (4-tuple).

__len__()Link to this definition#

Mengembalikan sejumlah titik dalam sebuah LineString, sejumlah geometri dalam sebuah GeometryCollection. Tidak diberlakukan ke jenis geometri lain.

__iter__()Link to this definition#

Iterates over the points in a LineString, the rings in a Polygon, or the geometries in a GeometryCollection. Not applicable to other geometry types.

__getitem__()Link to this definition#

Returns the point at the specified index for a LineString, the interior ring at the specified index for a Polygon, or the geometry at the specified index in a GeometryCollection. Not applicable to other geometry types.

dimensionLink to this definition#

Mengembalikan sejumlah dimensi kordinat dari geometri, yaitu 0 untuk titik, 1 untuk baris, dan sebagainya:

Code

>> polygon.dimension
2

coord_dimLink to this definition#

Returns or sets the coordinate dimension of this geometry. For example, the value would be 2 for two-dimensional geometries.

geom_countLink to this definition#

Mengembalikan sejumlah unsur dalam geometri ini:

Code

>>> polygon.geom_count
1

point_countLink to this definition#

Mengembalikan sejumlah titik digunakan untuk menggambarkan geometri ini:

Code

>>> polygon.point_count
4

num_pointsLink to this definition#

Nama lain untuk point_count.

num_coordsLink to this definition#

Nama lain untuk point_count.

geom_typeLink to this definition#

Mengembalikan jenis dari geometri ini, sebagai sebuah obyek OGRGeomType.

geom_nameLink to this definition#

Mengembalikan nama dari jenis dari geometri ini:

Code

>>> polygon.geom_name
'POLYGON'

areaLink to this definition#

Mengembalikan kawasan dari geometri ini, atau 0 untuk geometri yang tidak mengandung sebuah kawasan:

Code

>>> polygon.area
25.0

envelopeLink to this definition#

Mengembalikan sampul dari geometri ini, sebagai sebuah obyek Envelope.

extentLink to this definition#

Returns the envelope of this geometry as a 4-tuple, instead of as an Envelope object:

Code

>>> point.extent
(0.0, 0.0, 5.0, 5.0)

srsLink to this definition#

Sifat ini mengendalikan acuan spasial untuk geometri ini, atau None jika tidak ada sisterm acuan spasia telah diberikan ke itu. Jika diberikan, mengakses sifat ini mengembalikan sebuah obyek SpatialReference. Itu mungkin disetel dengan obyek SpatialReference lain, atau masukan apapun yang SpatialReference terima. Contoh:

Code

>>> city.geom.srs.name
'GCS_WGS_1984'

sridLink to this definition#

Returns or sets the spatial reference identifier corresponding to SpatialReference of this geometry. Returns None if there is no spatial reference information associated with this geometry, or if an SRID cannot be determined.

geosLink to this definition#

Returns a GEOSGeometry object corresponding to this geometry.

gmlLink to this definition#

Returns a string representation of this geometry in GML format:

Code

>>> OGRGeometry('POINT(1 2)').gml
'<gml:Point><gml:coordinates>1,2</gml:coordinates></gml:Point>'

hexLink to this definition#

Returns a string representation of this geometry in HEX WKB format:

Code

>>> OGRGeometry('POINT(1 2)').hex
'0101000000000000000000F03F0000000000000040'

jsonLink to this definition#

Mengembalikan string perwakilan dari geometri ini dalam bentuk JSON:

Code

>>> OGRGeometry('POINT(1 2)').json
'{ "type": "Point", "coordinates": [ 1.000000, 2.000000 ] }'

kmlLink to this definition#

Returns a string representation of this geometry in KML format.

wkb_sizeLink to this definition#

Returns the size of the WKB buffer needed to hold a WKB representation of this geometry:

Code

>>> OGRGeometry('POINT(1 2)').wkb_size
21

wkbLink to this definition#

Returns a buffer containing a WKB representation of this geometry.

wktLink to this definition#

Returns a string representation of this geometry in WKT format.

ewktLink to this definition#

Returns the EWKT representation of this geometry.

clone()Link to this definition#

Returns a new OGRGeometry clone of this geometry object.

close_rings()Link to this definition#

If there are any rings within this geometry that have not been closed, this routine will do so by adding the starting point to the end:

Code

>>> triangle = OGRGeometry('LINEARRING (0 0,0 1,1 0)')
>>> triangle.close_rings()
>>> triangle.wkt
'LINEARRING (0 0,0 1,1 0,0 0)'

transform(coord_trans, clone=False)Link to this definition#

Transforms this geometry to a different spatial reference system. May take a CoordTransform object, a SpatialReference object, or any other input accepted by SpatialReference (including spatial reference WKT and PROJ.4 strings, or an integer SRID).

By default nothing is returned and the geometry is transformed in-place. However, if the clone keyword is set to True then a transformed clone of this geometry is returned instead.

intersects(other)Link to this definition#

Returns True if this geometry intersects the other, otherwise returns False.

equals(other)Link to this definition#

Returns True if this geometry is equivalent to the other, otherwise returns False.

disjoint(other)Link to this definition#

Returns True if this geometry is spatially disjoint to (i.e. does not intersect) the other, otherwise returns False.

touches(other)Link to this definition#

Returns True if this geometry touches the other, otherwise returns False.

crosses(other)Link to this definition#

Returns True if this geometry crosses the other, otherwise returns False.

within(other)Link to this definition#

Returns True if this geometry is contained within the other, otherwise returns False.

contains(other)Link to this definition#

Returns True if this geometry contains the other, otherwise returns False.

overlaps(other)Link to this definition#

Returns True if this geometry overlaps the other, otherwise returns False.

boundary()Link to this definition#

The boundary of this geometry, as a new OGRGeometry object.

convex_hullLink to this definition#

The smallest convex polygon that contains this geometry, as a new OGRGeometry object.

difference()Link to this definition#

Returns the region consisting of the difference of this geometry and the other, as a new OGRGeometry object.

intersection()Link to this definition#

Returns the region consisting of the intersection of this geometry and the other, as a new OGRGeometry object.

sym_difference()Link to this definition#

Returns the region consisting of the symmetric difference of this geometry and the other, as a new OGRGeometry object.

union()Link to this definition#

Returns the region consisting of the union of this geometry and the other, as a new OGRGeometry object.

tupleLink to this definition#

Mengembalikan kordinat-kordinat dari titik geometri sebagai sebuah tuple, kordinat-kordinat dari baris geometri sebagai sebuah tuple dari tuple, dan sebagainya:

Code

>>> OGRGeometry('POINT (1 2)').tuple
(1.0, 2.0)
>>> OGRGeometry('LINESTRING (1 2,3 4)').tuple
((1.0, 2.0), (3.0, 4.0))

coordsLink to this definition#

Sebuah nama lain untuk tuple.

class PointLink to this definition#

xLink to this definition#

Mengembalikan kordinat X dari titik ini:

Code

>>> OGRGeometry('POINT (1 2)').x
1.0

yLink to this definition#

Mengembalikan kordinat Y dari titik ini:

Code

>>> OGRGeometry('POINT (1 2)').y
2.0

zLink to this definition#

Returns the Z coordinate of this point, or None if the point does not have a Z coordinate:

Code

>>> OGRGeometry('POINT (1 2 3)').z
3.0

class LineStringLink to this definition#

xLink to this definition#

Mengembalikan sebuah daftar dari kordinat X dalam baris ini:

Code

>>> OGRGeometry('LINESTRING (1 2,3 4)').x
[1.0, 3.0]

yLink to this definition#

Mengembalikan sebuah daftar dari kordinat Y dalam baris ini:

Code

>>> OGRGeometry('LINESTRING (1 2,3 4)').y
[2.0, 4.0]

zLink to this definition#

Returns a list of Z coordinates in this line, or None if the line does not have Z coordinates:

Code

>>> OGRGeometry('LINESTRING (1 2 3,4 5 6)').z
[3.0, 6.0]

class PolygonLink to this definition#

shellLink to this definition#

Returns the shell or exterior ring of this polygon, as a LinearRing geometry.

exterior_ringLink to this definition#

Sebuah nama lain untuk shell.

centroidLink to this definition#

Returns a Point representing the centroid of this polygon.

class GeometryCollectionLink to this definition#

add(geom)Link to this definition#

Adds a geometry to this geometry collection. Not applicable to other geometry types.

OGRGeomTypeLink to this heading#

class OGRGeomType(type_input)Link to this definition#

Kelas ini mengizinkan untuk gambaran dari jenis geometri OGR dalam beberapa cara:

Code

>>> from django.contrib.gis.gdal import OGRGeomType
>>> gt1 = OGRGeomType(3)             # Using an integer for the type
>>> gt2 = OGRGeomType('Polygon')     # Using a string
>>> gt3 = OGRGeomType('POLYGON')     # It's case-insensitive
>>> print(gt1 == 3, gt1 == 'Polygon') # Equivalence works w/non-OGRGeomType objects
True True

nameLink to this definition#

Returns a short-hand string form of the OGR Geometry type:

Code

>>> gt1.name
'Polygon'

numLink to this definition#

Mengembalikan sejumlah kaitan pada jenis geometri OGR:

Code

>>> gt1.num
3

djangoLink to this definition#

Returns the Django field type (a subclass of GeometryField) to use for storing this OGR type, or None if there is no appropriate Django type:

Code

>>> gt1.django
'PolygonField'

EnvelopeLink to this heading#

class Envelope(*args)Link to this definition#

Represents an OGR Envelope structure that contains the minimum and maximum X, Y coordinates for a rectangle bounding box. The naming of the variables is compatible with the OGR Envelope C structure.

min_xLink to this definition#

Nilai minimal kordinat X

min_yLink to this definition#

Nilai maksimal kordinat X.

max_xLink to this definition#

Nilai minimal kordinat Y.

max_yLink to this definition#

Nilai maksimal kordinat Y.

urLink to this definition#

Kordinat atas-kanan, sebagai sebuah tuple.

llLink to this definition#

Kordinat kiri-bawah, sebagai sebuah tuple.

tupleLink to this definition#

A tuple representing the envelope.

wktLink to this definition#

A string representing this envelope as a polygon in WKT format.

expand_to_include(*args)Link to this definition#

SpatialReferenceLink to this heading#

class SpatialReference(srs_input)Link to this definition#

Spatial reference objects are initialized on the given srs_input, which may be one of the following:

• OGC Well Known Text (WKT) (sebuah string)

• Kode EPSG(integer atau string)

• String PROJ.4

• A shorthand string for well-known standards ('WGS84', 'WGS72', 'NAD27', 'NAD83')

Contoh:

Code

>>> wgs84 = SpatialReference('WGS84') # shorthand string
>>> wgs84 = SpatialReference(4326) # EPSG code
>>> wgs84 = SpatialReference('EPSG:4326') # EPSG string
>>> proj4 = '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs '
>>> wgs84 = SpatialReference(proj4) # PROJ.4 string
>>> wgs84 = SpatialReference("""GEOGCS["WGS 84",
DATUM["WGS_1984",
     SPHEROID["WGS 84",6378137,298.257223563,
         AUTHORITY["EPSG","7030"]],
     AUTHORITY["EPSG","6326"]],
 PRIMEM["Greenwich",0,
     AUTHORITY["EPSG","8901"]],
 UNIT["degree",0.01745329251994328,
     AUTHORITY["EPSG","9122"]],
 AUTHORITY["EPSG","4326"]]""") # OGC WKT

__getitem__(target)Link to this definition#

Returns the value of the given string attribute node, None if the node doesn't exist. Can also take a tuple as a parameter, (target, child), where child is the index of the attribute in the WKT. For example:

Code

>>> wkt = 'GEOGCS["WGS 84", DATUM["WGS_1984, ... AUTHORITY["EPSG","4326"]]')
>>> srs = SpatialReference(wkt) # could also use 'WGS84', or 4326
>>> print(srs['GEOGCS'])
WGS 84
>>> print(srs['DATUM'])
WGS_1984
>>> print(srs['AUTHORITY'])
EPSG
>>> print(srs['AUTHORITY', 1]) # The authority value
4326
>>> print(srs['TOWGS84', 4]) # the fourth value in this wkt
0
>>> print(srs['UNIT|AUTHORITY']) # For the units authority, have to use the pipe symbol.
EPSG
>>> print(srs['UNIT|AUTHORITY', 1]) # The authority value for the units
9122

attr_value(target, index=0)Link to this definition#

The attribute value for the given target node (e.g. 'PROJCS'). The index keyword specifies an index of the child node to return.

auth_name(target)Link to this definition#

Returns the authority name for the given string target node.

auth_code(target)Link to this definition#

Returns the authority code for the given string target node.

clone()Link to this definition#

Returns a clone of this spatial reference object.

identify_epsg()Link to this definition#

Metode ini memeriksa WKT dari SpatialReference ini dan akan menambahkan node-node wewenang EPSG dimana sebuah penciri EPSG dapat diterapkan.

from_esri()Link to this definition#

Morphs this SpatialReference from ESRI's format to EPSG

to_esri()Link to this definition#

Morphs this SpatialReference to ESRI's format.

validate()Link to this definition#

Memeriksa untuk melihat jika acuan spasial diberikan adalah sah, jika tidak sebuah pengecualian akan dimunculkan.

import_epsg(epsg)Link to this definition#

Import spatial reference from EPSG code.

import_proj(proj)Link to this definition#

Import spatial reference from PROJ.4 string.

import_user_input(user_input)Link to this definition#

import_wkt(wkt)Link to this definition#

Import spatial reference from WKT.

import_xml(xml)Link to this definition#

Import spatial reference from XML.

nameLink to this definition#

Returns the name of this Spatial Reference.

sridLink to this definition#

Returns the SRID of top-level authority, or None if undefined.

linear_nameLink to this definition#

Returns the name of the linear units.

linear_unitsLink to this definition#

Returns the value of the linear units.

angular_nameLink to this definition#

Returns the name of the angular units."

angular_unitsLink to this definition#

Returns the value of the angular units.

unitsLink to this definition#

Returns a 2-tuple of the units value and the units name and will automatically determines whether to return the linear or angular units.

ellipsoidLink to this definition#

Returns a tuple of the ellipsoid parameters for this spatial reference: (semimajor axis, semiminor axis, and inverse flattening).

semi_majorLink to this definition#

Returns the semi major axis of the ellipsoid for this spatial reference.

semi_minorLink to this definition#

Returns the semi minor axis of the ellipsoid for this spatial reference.

inverse_flatteningLink to this definition#

Returns the inverse flattening of the ellipsoid for this spatial reference.

geographicLink to this definition#

Returns True if this spatial reference is geographic (root node is GEOGCS).

localLink to this definition#

Returns True if this spatial reference is local (root node is LOCAL_CS).

projectedLink to this definition#

Returns True if this spatial reference is a projected coordinate system (root node is PROJCS).

wktLink to this definition#

Returns the WKT representation of this spatial reference.

pretty_wktLink to this definition#

Returns the 'pretty' representation of the WKT.

projLink to this definition#

Returns the PROJ.4 representation for this spatial reference.

proj4Link to this definition#

Nama lain untuk SpatialReference.proj.

xmlLink to this definition#

Returns the XML representation of this spatial reference.

CoordTransformLink to this heading#

class CoordTransform(source, target)Link to this definition#

Represents a coordinate system transform. It is initialized with two SpatialReference, representing the source and target coordinate systems, respectively. These objects should be used when performing the same coordinate transformation repeatedly on different geometries:

>>> ct = CoordTransform(SpatialReference('WGS84'), SpatialReference('NAD83'))
>>> for feat in layer:
...     geom = feat.geom # getting clone of feature geometry
...     geom.transform(ct) # transforming

GDALRasterLink to this heading#

GDALRaster is a wrapper for the GDAL raster source object that supports reading data from a variety of GDAL-supported geospatial file formats and data sources using a simple, consistent interface. Each data source is represented by a GDALRaster object which contains one or more layers of data named bands. Each band, represented by a GDALBand object, contains georeferenced image data. For example, an RGB image is represented as three bands: one for red, one for green, and one for blue.

class GDALRaster(ds_input, write=False)Link to this definition#

The constructor for GDALRaster accepts two parameters. The first parameter defines the raster source, it is either a path to a file or spatial data with values defining the properties of a new raster (such as size and name). If the input is a file path, the second parameter specifies if the raster should be opened with write access. If the input is raw data, the parameters width, height, and srid are required. The following example shows how rasters can be created from different input sources (using the sample data from the GeoDjango tests, see also the Data Contoh section). For a detailed description of how to create rasters using dictionary input, see the Membuat raster dari data section.

Code

>>> from django.contrib.gis.gdal import GDALRaster
>>> rst = GDALRaster('/path/to/your/raster.tif', write=False)
>>> rst.name
'/path/to/your/raster.tif'
>>> rst.width, rst.height  # This file has 163 x 174 pixels
(163, 174)
>>> rst = GDALRaster({  # Creates an in-memory raster
...     'srid': 4326,
...     'width': 4,
...     'height': 4,
...     'datatype': 1,
...     'bands': [{
...         'data': (2, 3),
...         'offset': (1, 1),
...         'size': (2, 2),
...         'shape': (2, 1),
...         'nodata_value': 5,
...     }]
... })
>>> rst.srs.srid
4326
>>> rst.width, rst.height
(4, 4)
>>> rst.bands[0].data()
array([[5, 5, 5, 5],
       [5, 2, 3, 5],
       [5, 2, 3, 5],
       [5, 5, 5, 5]], dtype=uint8)

nameLink to this definition#

The name of the source which is equivalent to the input file path or the name provided upon instantiation.

Code

>>> GDALRaster({'width': 10, 'height': 10, 'name': 'myraster', 'srid': 4326}).name
'myraster'

driverLink to this definition#

The name of the GDAL driver used to handle the input file. For GDALRasters created from a file, the driver type is detected automatically. The creation of rasters from scratch is a in-memory raster by default ('MEM'), but can be altered as needed. For instance, use GTiff for a GeoTiff file. For a list of file types, see also the GDAL Raster Formats list.

An in-memory raster is created through the following example:

Code

>>> GDALRaster({'width': 10, 'height': 10, 'srid': 4326}).driver.name
'MEM'

A file based GeoTiff raster is created through the following example:

Code

>>> import tempfile
>>> rstfile = tempfile.NamedTemporaryFile(suffix='.tif')
>>> rst = GDALRaster({'driver': 'GTiff', 'name': rstfile.name, 'srid': 4326,
...                   'width': 255, 'height': 255, 'nr_of_bands': 1})
>>> rst.name
'/tmp/tmp7x9H4J.tif'           # The exact filename will be different on your computer
>>> rst.driver.name
'GTiff'

widthLink to this definition#

The width of the source in pixels (X-axis).

Code

>>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).width
10

heightLink to this definition#

The height of the source in pixels (Y-axis).

Code

>>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).height
20

srsLink to this definition#

The spatial reference system of the raster, as a SpatialReference instance. The SRS can be changed by setting it to an other SpatialReference or providing any input that is accepted by the SpatialReference constructor.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.srs.srid
4326
>>> rst.srs = 3086
>>> rst.srs.srid
3086

sridLink to this definition#

The Spatial Reference System Identifier (SRID) of the raster. This property is a shortcut to getting or setting the SRID through the srs attribute.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.srid
4326
>>> rst.srid = 3086
>>> rst.srid
3086
>>> rst.srs.srid  # This is equivalent
3086

geotransformLink to this definition#

The affine transformation matrix used to georeference the source, as a tuple of six coefficients which map pixel/line coordinates into georeferenced space using the following relationship:

Code

Xgeo = GT(0) + Xpixel*GT(1) + Yline*GT(2)
Ygeo = GT(3) + Xpixel*GT(4) + Yline*GT(5)

The same values can be retrieved by accessing the origin (indices 0 and 3), scale (indices 1 and 5) and skew (indices 2 and 4) properties.

Awalnya adalah [0.0, 1.0, 0.0, 0.0, 0.0, -1.0].

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.geotransform
[0.0, 1.0, 0.0, 0.0, 0.0, -1.0]

originLink to this definition#

Coordinates of the top left origin of the raster in the spatial reference system of the source, as a point object with x and y members.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.origin
[0.0, 0.0]
>>> rst.origin.x = 1
>>> rst.origin
[1.0, 0.0]

scaleLink to this definition#

Pixel width and height used for georeferencing the raster, as a as a point object with x and y members. See geotransform for more information.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.scale
[1.0, -1.0]
>>> rst.scale.x = 2
>>> rst.scale
[2.0, -1.0]

skewLink to this definition#

Skew coefficients used to georeference the raster, as a point object with x and y members. In case of north up images, these coefficients are both 0.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.skew
[0.0, 0.0]
>>> rst.skew.x = 3
>>> rst.skew
[3.0, 0.0]

extentLink to this definition#

Extent (boundary values) of the raster source, as a 4-tuple (xmin, ymin, xmax, ymax) in the spatial reference system of the source.

Code

>>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326})
>>> rst.extent
(0.0, -20.0, 10.0, 0.0)
>>> rst.origin.x = 100
>>> rst.extent
(100.0, -20.0, 110.0, 0.0)

bandsLink to this definition#

List of all bands of the source, as GDALBand instances.

Code

>>> rst = GDALRaster({"width": 1, "height": 2, 'srid': 4326,
...                   "bands": [{"data": [0, 1]}, {"data": [2, 3]}]})
>>> len(rst.bands)
2
>>> rst.bands[1].data()
array([[ 2.,  3.]], dtype=float32)

warp(ds_input, resampling='NearestNeighbour', max_error=0.0)Link to this definition#

Returns a warped version of this raster.

The warping parameters can be specified through the ds_input argument. The use of ds_input is analogous to the corresponding argument of the class constructor. It is a dictionary with the characteristics of the target raster. Allowed dictionary key values are width, height, SRID, origin, scale, skew, datatype, driver, and name (filename).

By default, the warp functions keeps most parameters equal to the values of the original source raster, so only parameters that should be changed need to be specified. Note that this includes the driver, so for file-based rasters the warp function will create a new raster on disk.

The only parameter that is set differently from the source raster is the name. The default value of the the raster name is the name of the source raster appended with '_copy' + source_driver_name. For file-based rasters it is recommended to provide the file path of the target raster.

The resampling algorithm used for warping can be specified with the resampling argument. The default is NearestNeighbor, and the other allowed values are Bilinear, Cubic, CubicSpline, Lanczos, Average, and Mode.

The max_error argument can be used to specify the maximum error measured in input pixels that is allowed in approximating the transformation. The default is 0.0 for exact calculations.

Untuk pengguna akrab dengan GDAL, fungsi ini mempunyai fungsionalitas mirip pada kegunaan baris-perintah gdalwarp.

For example, the warp function can be used for aggregating a raster to the double of its original pixel scale:

Code

>>> rst = GDALRaster({
...     "width": 6, "height": 6, "srid": 3086,
...     "origin": [500000, 400000],
...     "scale": [100, -100],
...     "bands": [{"data": range(36), "nodata_value": 99}]
... })
>>> target = rst.warp({"scale": [200, -200], "width": 3, "height": 3})
>>> target.bands[0].data()
array([[  7.,   9.,  11.],
       [ 19.,  21.,  23.],
       [ 31.,  33.,  35.]], dtype=float32)

transform(srid, driver=None, name=None, resampling='NearestNeighbour', max_error=0.0)Link to this definition#

Returns a transformed version of this raster with the specified SRID.

This function transforms the current raster into a new spatial reference system that can be specified with an srid. It calculates the bounds and scale of the current raster in the new spatial reference system and warps the raster using the warp function.

By default, the driver of the source raster is used and the name of the raster is the original name appended with '_copy' + source_driver_name. A different driver or name can be specified with the driver and name arguments.

The default resampling algorithm is NearestNeighbour but can be changed using the resampling argument. The default maximum allowed error for resampling is 0.0 and can be changed using the max_error argument. Consult the warp documentation for detail on those arguments.

Code

>>> rst = GDALRaster({
...     "width": 6, "height": 6, "srid": 3086,
...     "origin": [500000, 400000],
...     "scale": [100, -100],
...     "bands": [{"data": range(36), "nodata_value": 99}]
... })
>>> target = rst.transform(4326)
>>> target.origin
[-82.98492744885776, 27.601924753080144]

GDALBandLink to this heading#

class GDALBandLink to this definition#

GDALBand instances are not created explicitly, but rather obtained from a GDALRaster object, through its bands attribute. The GDALBands contain the actual pixel values of the raster.

descriptionLink to this definition#

Nama dari gambaran dari pita, jika ada.

widthLink to this definition#

The width of the band in pixels (X-axis).

heightLink to this definition#

The height of the band in pixels (Y-axis).

pixel_countLink to this definition#

The total number of pixels in this band. Is equal to width * height.

statistics(refresh=False, approximate=False)Link to this definition#

Compute statistics on the pixel values of this band. The return value is a tuple with the following structure: (minimum, maximum, mean, standard deviation).

If the approximate argument is set to True, the statistics may be computed based on overviews or a subset of image tiles.

If the refresh argument is set to True, the statistics will be computed from the data directly, and the cache will be updated with the result.

If a persistent cache value is found, that value is returned. For raster formats using Persistent Auxiliary Metadata (PAM) services, the statistics might be cached in an auxiliary file. In some cases this metadata might be out of sync with the pixel values or cause values from a previous call to be returned which don't reflect the value of the approximate argument. In such cases, use the refresh argument to get updated values and store them in the cache.

For empty bands (where all pixel values are "no data"), all statistics are returned as None.

The statistics can also be retrieved directly by accessing the min, max, mean, and std properties.

minLink to this definition#

The minimum pixel value of the band (excluding the "no data" value).

maxLink to this definition#

The maximum pixel value of the band (excluding the "no data" value).

meanLink to this definition#

The mean of all pixel values of the band (excluding the "no data" value).

stdLink to this definition#

The standard deviation of all pixel values of the band (excluding the "no data" value).

nodata_valueLink to this definition#

The "no data" value for a band is generally a special marker value used to mark pixels that are not valid data. Such pixels should generally not be displayed, nor contribute to analysis operations.

To delete an existing "no data" value, set this property to None (requires GDAL ≥ 2.1).

datatype(as_string=False)Link to this definition#

The data type contained in the band, as an integer constant between 0 (Unknown) and 11. If as_string is True, the data type is returned as a string with the following possible values: GDT_Unknown, GDT_Byte, GDT_UInt16, GDT_Int16, GDT_UInt32, GDT_Int32, GDT_Float32, GDT_Float64, GDT_CInt16, GDT_CInt32, GDT_CFloat32, and GDT_CFloat64.

data(data=None, offset=None, size=None, shape=None)Link to this definition#

The accessor to the pixel values of the GDALBand. Returns the complete data array if no parameters are provided. A subset of the pixel array can be requested by specifying an offset and block size as tuples.

If NumPy is available, the data is returned as NumPy array. For performance reasons, it is highly recommended to use NumPy.

Data is written to the GDALBand if the data parameter is provided. The input can be of one of the following types - packed string, buffer, list, array, and NumPy array. The number of items in the input should normally correspond to the total number of pixels in the band, or to the number of pixels for a specific block of pixel values if the offset and size parameters are provided.

If the number of items in the input is different from the target pixel block, the shape parameter must be specified. The shape is a tuple that specifies the width and height of the input data in pixels. The data is then replicated to update the pixel values of the selected block. This is useful to fill an entire band with a single value, for instance.

Sebagai contoh:

Code

>>> rst = GDALRaster({'width': 4, 'height': 4, 'srid': 4326, 'datatype': 1, 'nr_of_bands': 1})
>>> bnd = rst.bands[0]
>>> bnd.data(range(16))
>>> bnd.data()
array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11],
       [12, 13, 14, 15]], dtype=int8)
>>> bnd.data(offset=(1, 1), size=(2, 2))
array([[ 5,  6],
       [ 9, 10]], dtype=int8)
>>> bnd.data(data=[-1, -2, -3, -4], offset=(1, 1), size=(2, 2))
>>> bnd.data()
array([[ 0,  1,  2,  3],
       [ 4, -1, -2,  7],
       [ 8, -3, -4, 11],
       [12, 13, 14, 15]], dtype=int8)
>>> bnd.data(data='\x9d\xa8\xb3\xbe', offset=(1, 1), size=(2, 2))
>>> bnd.data()
array([[  0,   1,   2,   3],
       [  4, -99, -88,   7],
       [  8, -77, -66,  11],
       [ 12,  13,  14,  15]], dtype=int8)
>>> bnd.data([1], shape=(1, 1))
>>> bnd.data()
array([[1, 1, 1, 1],
       [1, 1, 1, 1],
       [1, 1, 1, 1],
       [1, 1, 1, 1]], dtype=uint8)
>>> bnd.data(range(4), shape=(1, 4))
array([[0, 0, 0, 0],
       [1, 1, 1, 1],
       [2, 2, 2, 2],
       [3, 3, 3, 3]], dtype=uint8)

Membuat raster dari dataLink to this heading#

This section describes how to create rasters from scratch using the ds_input parameter.

A new raster is created when a dict is passed to the GDALRaster constructor. The dictionary contains defining parameters of the new raster, such as the origin, size, or spatial reference system. The dictionary can also contain pixel data and information about the format of the new raster. The resulting raster can therefore be file-based or memory-based, depending on the driver specified.

There's no standard for describing raster data in a dictionary or JSON flavor. The definition of the dictionary input to the GDALRaster class is therefore specific to Django. It's inspired by the geojson format, but the geojson standard is currently limited to vector formats.

Examples of using the different keys when creating rasters can be found in the documentation of the corresponding attributes and methods of the GDALRaster and GDALBand classes.

GDAL_LIBRARY_PATHLink to this heading#

A string specifying the location of the GDAL library. Typically, this setting is only used if the GDAL library is in a non-standard location (e.g., /home/john/lib/libgdal.so).