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Hotel/env/lib/python3.5/site-packages/django/contrib/gis/gdal/feature.py

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from django.contrib.gis.gdal.base import GDALBase
from django.contrib.gis.gdal.error import GDALException
from django.contrib.gis.gdal.field import Field
from django.contrib.gis.gdal.geometries import OGRGeometry, OGRGeomType
from django.contrib.gis.gdal.prototypes import ds as capi, geom as geom_api
from django.utils.encoding import force_bytes, force_text
# For more information, see the OGR C API source code:
# https://www.gdal.org/ogr__api_8h.html
#
# The OGR_F_* routines are relevant here.
class Feature(GDALBase):
"""
This class that wraps an OGR Feature, needs to be instantiated
from a Layer object.
"""
destructor = capi.destroy_feature
def __init__(self, feat, layer):
"""
Initialize Feature from a pointer and its Layer object.
"""
if not feat:
raise GDALException('Cannot create OGR Feature, invalid pointer given.')
self.ptr = feat
self._layer = layer
def __getitem__(self, index):
"""
Get the Field object at the specified index, which may be either
an integer or the Field's string label. Note that the Field object
is not the field's _value_ -- use the `get` method instead to
retrieve the value (e.g. an integer) instead of a Field instance.
"""
if isinstance(index, str):
i = self.index(index)
elif 0 <= index < self.num_fields:
i = index
else:
raise IndexError('Index out of range when accessing field in a feature: %s.' % index)
return Field(self, i)
def __len__(self):
"Return the count of fields in this feature."
return self.num_fields
def __str__(self):
"The string name of the feature."
return 'Feature FID %d in Layer<%s>' % (self.fid, self.layer_name)
def __eq__(self, other):
"Do equivalence testing on the features."
return bool(capi.feature_equal(self.ptr, other._ptr))
# #### Feature Properties ####
@property
def encoding(self):
return self._layer._ds.encoding
@property
def fid(self):
"Return the feature identifier."
return capi.get_fid(self.ptr)
@property
def layer_name(self):
"Return the name of the layer for the feature."
name = capi.get_feat_name(self._layer._ldefn)
return force_text(name, self.encoding, strings_only=True)
@property
def num_fields(self):
"Return the number of fields in the Feature."
return capi.get_feat_field_count(self.ptr)
@property
def fields(self):
"Return a list of fields in the Feature."
return [
force_text(
capi.get_field_name(capi.get_field_defn(self._layer._ldefn, i)),
self.encoding,
strings_only=True
) for i in range(self.num_fields)
]
@property
def geom(self):
"Return the OGR Geometry for this Feature."
# Retrieving the geometry pointer for the feature.
geom_ptr = capi.get_feat_geom_ref(self.ptr)
return OGRGeometry(geom_api.clone_geom(geom_ptr))
@property
def geom_type(self):
"Return the OGR Geometry Type for this Feature."
return OGRGeomType(capi.get_fd_geom_type(self._layer._ldefn))
# #### Feature Methods ####
def get(self, field):
"""
Return the value of the field, instead of an instance of the Field
object. May take a string of the field name or a Field object as
parameters.
"""
field_name = getattr(field, 'name', field)
return self[field_name].value
def index(self, field_name):
"Return the index of the given field name."
i = capi.get_field_index(self.ptr, force_bytes(field_name))
if i < 0:
raise IndexError('Invalid OFT field name given: %s.' % field_name)
return i