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gis: Added an intial ctypes interface to GDAL/OGR
 (1) SpatialReference allows for rich access to properties of spatial reference systems. (2) OGRGeometry provides access to the OGR Geometry classes -- may be accessed from models with the get_GEOM_ogr() extra instance method. git-svn-id: http://code.djangoproject.com/svn/django/branches/gis@5397 bcc190cf-cafb-0310-a4f2-bffc1f526a37
1 parent 38ff3cf commit b962a44

27 files changed

+1674
-31
lines changed

‎django/contrib/gis/db/models/GeoMixin.py

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# GEOS Routines
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from django.contrib.gis.geos import GEOSGeometry, hex_to_wkt, centroid, area
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from django.contrib.gis.gdal import OGRGeometry, SpatialReference
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# Until model subclassing is a possibility, a mixin class is used to add
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# the necessary functions that may be contributed for geographic objects.
@@ -12,6 +13,11 @@ def _get_GEOM_geos(self, field):
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"Gets a GEOS Python object for the geometry."
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return GEOSGeometry(getattr(self, field.attname), 'hex')
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def _get_GEOM_ogr(self, field, srid):
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"Gets an OGR Python object for the geometry."
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return OGRGeometry(hex_to_wkt(getattr(self, field.attname)),
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SpatialReference('EPSG:%d' % srid))
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def _get_GEOM_wkt(self, field):
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"Gets the WKT of the geometry."
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hex = getattr(self, field.attname)

‎django/contrib/gis/db/models/fields/__init__.py

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from django.contrib.gis.geos import GEOSGeometry, GEOSException
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#TODO: Flesh out widgets.
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#TODO: geos operations through fields as proxy.
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#TODO: GEOS and GDAL/OGR operations through fields as proxy.
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#TODO: pythonic usage, like "for point in zip.polygon" and "if point in polygon".
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class GeometryField(Field):
@@ -38,8 +38,7 @@ def _add_geom(self, style, db_table, field):
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AddGeometryColumn(...) PostGIS (and OGC standard) function.
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Takes the style object (provides syntax highlighting) as well as the
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database table and field. The dimensions can be specified via
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the dim keyword as well.
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database table and field.
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"""
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sql = style.SQL_KEYWORD('SELECT ') + \
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style.SQL_TABLE('AddGeometryColumn') + '(' + \
@@ -81,8 +80,9 @@ def _post_create_sql(self, style, db_table, field):
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def contribute_to_class(self, cls, name):
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super(GeometryField, self).contribute_to_class(cls, name)
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# Adding the WKT accessor function for geometry
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# Adding needed accessor functions
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setattr(cls, 'get_%s_geos' % self.name, curry(cls._get_GEOM_geos, field=self))
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setattr(cls, 'get_%s_ogr' % self.name, curry(cls._get_GEOM_ogr, field=self, srid=self._srid))
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setattr(cls, 'get_%s_wkt' % self.name, curry(cls._get_GEOM_wkt, field=self))
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setattr(cls, 'get_%s_centroid' % self.name, curry(cls._get_GEOM_centroid, field=self))
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setattr(cls, 'get_%s_area' % self.name, curry(cls._get_GEOM_area, field=self))

‎django/contrib/gis/db/models/postgis.py

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# This module is meant to re-define the helper routines used by the
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# django.db.models.query objects to be customized for PostGIS.
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from copy import copy
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from django.db import backend
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from django.db.models.query import LOOKUP_SEPARATOR, find_field, FieldFound, QUERY_TERMS, get_where_clause
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from django.utils.datastructures import SortedDict

‎django/contrib/gis/gdal/DataSource.py

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# types and ctypes
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from types import StringType
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from ctypes import c_char_p, c_int, c_void_p, byref, string_at
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# The GDAL C library, OGR exceptions, and the Layer object.
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from django.contrib.gis.gdal.libgdal import lgdal
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from django.contrib.gis.gdal.OGRError import OGRException, check_err
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from django.contrib.gis.gdal.Layer import Layer
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"""
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DataSource is a wrapper for the OGR Data Source object, which provides
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an interface for reading vector geometry data from many different file
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formats (including ESRI shapefiles).
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Example:
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ds = DataSource('/home/foo/bar.shp')
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for layer in ds:
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for feature in layer:
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# Getting the geometry for the feature.
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g = feature.geom
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# Getting the 'description' field for the feature.
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desc = feature['description']
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More documentation forthcoming.
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"""
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# For more information, see the OGR C API source code:
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# http://www.gdal.org/ogr/ogr__api_8h.html
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#
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# The OGR_DS* routines are relevant here.
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class DataSource(object):
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"Wraps an OGR Data Source object."
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_ds = 0 # Initially NULL
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#### Python 'magic' routines ####
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def __init__(self, ds_file):
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# Registering all the drivers, this needs to be done
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# _before_ we try to open up a data source.
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if not lgdal.OGRRegisterAll():
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raise OGRException, 'Could not register all data source drivers!'
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# The data source driver is a void pointer.
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ds_driver = c_void_p()
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# OGROpen will auto-detect the data source type.
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ds = lgdal.OGROpen(c_char_p(ds_file), c_int(0), byref(ds_driver))
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# Raise an exception if the returned pointer is NULL
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if not ds:
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self._ds = False
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raise OGRException, 'Invalid data source file "%s"' % ds_file
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else:
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self._ds = ds
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self._driver = ds_driver
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def __del__(self):
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"This releases the reference to the data source (destroying it if it's the only one)."
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if self._ds: lgdal.OGRReleaseDataSource(self._ds)
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def __iter__(self):
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"Allows for iteration over the layers in a data source."
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for i in xrange(self.layer_count):
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yield self.__getitem__(i)
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def __getitem__(self, index):
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"Allows use of the index [] operator to get a layer at the index."
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if isinstance(index, StringType):
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l = lgdal.OGR_DS_GetLayerByName(self._ds, c_char_p(index))
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if not l: raise IndexError, 'invalid OGR Layer name given: "%s"' % index
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else:
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if index < 0 or index >= self.layer_count:
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raise IndexError, 'index out of range'
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l = lgdal.OGR_DS_GetLayer(self._ds, c_int(index))
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return Layer(l)
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def __len__(self):
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"Returns the number of layers within the data source."
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return self.layer_count
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def __str__(self):
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"Returns OGR GetName and Driver for the Data Source."
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return '%s (%s)' % (self.name, self.driver)
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#### DataSource Properties ####
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@property
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def driver(self):
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"Returns the name of the data source driver."
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return string_at(lgdal.OGR_Dr_GetName(self._driver))
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@property
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def layer_count(self):
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"Returns the number of layers in the data source."
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return lgdal.OGR_DS_GetLayerCount(self._ds)
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@property
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def name(self):
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"Returns the name of the data source."
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return string_at(lgdal.OGR_DS_GetName(self._ds))
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‎django/contrib/gis/gdal/Feature.py

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# types and ctypes
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import types
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from ctypes import c_char_p, c_int, string_at
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# The GDAL C library, OGR exception, and the Field object
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from django.contrib.gis.gdal.libgdal import lgdal
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from django.contrib.gis.gdal.OGRError import OGRException
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from django.contrib.gis.gdal.Field import Field
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from django.contrib.gis.gdal.OGRGeometry import OGRGeometry, OGRGeomType
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# For more information, see the OGR C API source code:
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# http://www.gdal.org/ogr/ogr__api_8h.html
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#
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# The OGR_F_* routines are relevant here.
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class Feature(object):
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"A class that wraps an OGR Feature, needs to be instantiated from a Layer object."
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_feat = 0 # Initially NULL
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#### Python 'magic' routines ####
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def __init__(self, f):
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"Needs a C pointer (Python integer in ctypes) in order to initialize."
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if not f:
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raise OGRException, 'Cannot create OGR Feature, invalid pointer given.'
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self._feat = f
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self._fdefn = lgdal.OGR_F_GetDefnRef(f)
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def __del__(self):
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"Releases a reference to this object."
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if self._fdefn: lgdal.OGR_FD_Release(self._fdefn)
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def __getitem__(self, index):
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"Gets the Field at the specified index."
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if isinstance(index, types.StringType):
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i = self.index(index)
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else:
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if index < 0 or index > self.num_fields:
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raise IndexError, 'index out of range'
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i = index
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return Field(lgdal.OGR_F_GetFieldDefnRef(self._feat, c_int(i)),
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string_at(lgdal.OGR_F_GetFieldAsString(self._feat, c_int(i))))
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def __iter__(self):
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"Iterates over each field in the Feature."
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for i in xrange(self.num_fields):
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yield self.__getitem__(i)
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def __len__(self):
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"Returns the count of fields in this feature."
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return self.num_fields
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def __str__(self):
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"The string name of the feature."
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return 'Feature FID %d in Layer<%s>' % (self.fid, self.layer_name)
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def __eq__(self, other):
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"Does equivalence testing on the features."
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if lgdal.OGR_F_Equal(self._feat, other._feat):
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return True
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else:
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return False
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#### Feature Properties ####
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@property
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def fid(self):
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"Returns the feature identifier."
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return lgdal.OGR_F_GetFID(self._feat)
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@property
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def layer_name(self):
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"Returns the name of the layer for the feature."
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return string_at(lgdal.OGR_FD_GetName(self._fdefn))
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@property
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def num_fields(self):
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"Returns the number of fields in the Feature."
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return lgdal.OGR_F_GetFieldCount(self._feat)
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@property
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def fields(self):
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"Returns a list of fields in the Feature."
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return [ string_at(lgdal.OGR_Fld_GetNameRef(lgdal.OGR_FD_GetFieldDefn(self._fdefn, i)))
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for i in xrange(self.num_fields) ]
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@property
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def geom(self):
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"Returns the OGR Geometry for this Feature."
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# A clone is used, so destruction of the Geometry won't bork the Feature.
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return OGRGeometry(lgdal.OGR_G_Clone(lgdal.OGR_F_GetGeometryRef(self._feat)))
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@property
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def geom_type(self):
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"Returns the OGR Geometry Type for this Feture."
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return OGRGeomType(lgdal.OGR_FD_GetGeomType(self._fdefn))
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#### Feature Methods ####
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def index(self, field_name):
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"Returns the index of the given field name."
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i = lgdal.OGR_F_GetFieldIndex(self._feat, c_char_p(field_name))
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if i < 0: raise IndexError, 'invalid OFT field name given: "%s"' % field_name
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return i
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def clone(self):
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"Clones this Feature."
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return Feature(lgdal.OGR_F_Clone(self._feat))

‎django/contrib/gis/gdal/Field.py

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from ctypes import string_at
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from django.contrib.gis.gdal.libgdal import lgdal
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from django.contrib.gis.gdal.OGRError import OGRException
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# For more information, see the OGR C API source code:
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# http://www.gdal.org/ogr/ogr__api_8h.html
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#
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# The OGR_Fld_* routines are relevant here.
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class Field(object):
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"A class that wraps an OGR Field."
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_fld = 0 # Initially NULL
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#### Python 'magic' routines ####
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def __init__(self, fld, val=''):
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"Needs a C pointer (Python integer in ctypes) in order to initialize."
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if not fld:
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raise OGRException, 'Cannot create OGR Field, invalid pointer given.'
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self._fld = fld
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self._val = val
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# Setting the class depending upon the OGR Field Type (OFT)
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self.__class__ = FIELD_CLASSES[self.type]
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def __str__(self):
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"Returns the string representation of the Field."
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return '%s (%s)' % (self.name, self.__class__.__name__)
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#### Field Properties ####
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@property
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def name(self):
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"Returns the name of the field."
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return string_at(lgdal.OGR_Fld_GetNameRef(self._fld))
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@property
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def type(self):
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"Returns the type of this field."
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return lgdal.OGR_Fld_GetType(self._fld)
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@property
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def value(self):
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"Returns the value of this type of field."
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return self._val
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# The Field sub-classes for each OGR Field type.
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class OFTInteger(Field):
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@property
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def value(self):
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"Returns an integer contained in this field."
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return int(self._val)
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class OFTIntegerList(Field): pass
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class OFTReal(Field):
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@property
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def value(self):
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"Returns a float contained in this field."
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return float(self._val)
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class OFTRealList(Field): pass
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class OFTString(Field): pass
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class OFTStringList(Field): pass
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class OFTWideString(Field): pass
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class OFTWideStringList(Field): pass
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class OFTBinary(Field): pass
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class OFTDate(Field): pass
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class OFTTime(Field): pass
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class OFTDateTime(Field): pass
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# Class mapping dictionary for OFT Types
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FIELD_CLASSES = { 0 : OFTInteger,
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1 : OFTIntegerList,
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2 : OFTReal,
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3 : OFTRealList,
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4 : OFTString,
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5 : OFTStringList,
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6 : OFTWideString,
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7 : OFTWideStringList,
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8 : OFTBinary,
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9 : OFTDate,
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10 : OFTTime,
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11 : OFTDateTime,
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}

‎django/contrib/gis/gdal/LICENSE

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Copyright (c) 2007, Justin Bronn
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All rights reserved.
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Redistribution and use in source and binary forms, with or without modification,
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are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. Neither the name of OGRGeometry nor the names of its contributors may be used
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to endorse or promote products derived from this software without
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specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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