166 lines
5.6 KiB
Python
166 lines
5.6 KiB
Python
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"""Implementation of the intermediary layer between Shapely and GEOS
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This is layer number 2 from the list below.
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1) geometric objects: the Python OO API.
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2) implementation map: an abstraction that permits different backends.
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3) backend: callable objects that take Shapely geometric objects as arguments
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and, with GEOS as a backend, translate them to C data structures.
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4) GEOS library: algorithms implemented in C++.
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Shapely 1.2 includes a GEOS backend and it is the default.
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"""
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from functools import wraps
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from shapely.algorithms import cga
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from shapely.coords import BoundsOp
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from shapely.geos import lgeos
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from shapely.linref import ProjectOp, InterpolateOp
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from shapely.predicates import BinaryPredicate, UnaryPredicate
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from shapely.topology import BinaryRealProperty, BinaryTopologicalOp
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from shapely.topology import UnaryRealProperty, UnaryTopologicalOp
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class ImplementationError(
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AttributeError, KeyError, NotImplementedError):
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"""To be raised when the registered implementation does not
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support the requested method."""
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def delegated(func):
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"""A delegated method raises AttributeError in the absence of backend
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support."""
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@wraps(func)
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def wrapper(*args, **kwargs):
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try:
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return func(*args, **kwargs)
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except KeyError:
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raise ImplementationError(
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"Method '%s' not provided by registered "
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"implementation '%s'" % (func.__name__, args[0].impl))
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return wrapper
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# Map geometry methods to their GEOS delegates
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class BaseImpl(object):
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"""Base class for registrable implementations."""
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def __init__(self, values):
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self.map = dict(values)
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def update(self, values):
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self.map.update(values)
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def __getitem__(self, key):
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try:
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return self.map[key]
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except KeyError:
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raise ImplementationError(
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"Method '%s' not provided by registered "
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"implementation '%s'" % (key, self.map))
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def __contains__(self, key):
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return key in self.map
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class GEOSImpl(BaseImpl):
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"""GEOS implementation"""
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def __repr__(self):
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return '<GEOSImpl object: GEOS C API version %s>' % (
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lgeos.geos_capi_version,)
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IMPL300 = {
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'area': (UnaryRealProperty, 'area'),
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'distance': (BinaryRealProperty, 'distance'),
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'length': (UnaryRealProperty, 'length'),
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#
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'boundary': (UnaryTopologicalOp, 'boundary'),
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'bounds': (BoundsOp, None),
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'centroid': (UnaryTopologicalOp, 'centroid'),
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'representative_point': (UnaryTopologicalOp, 'representative_point'),
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'envelope': (UnaryTopologicalOp, 'envelope'),
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'convex_hull': (UnaryTopologicalOp, 'convex_hull'),
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'buffer': (UnaryTopologicalOp, 'buffer'),
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#
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'difference': (BinaryTopologicalOp, 'difference'),
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'intersection': (BinaryTopologicalOp, 'intersection'),
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'symmetric_difference': (BinaryTopologicalOp, 'symmetric_difference'),
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'union': (BinaryTopologicalOp, 'union'),
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#
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'has_z': (UnaryPredicate, 'has_z'),
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'is_empty': (UnaryPredicate, 'is_empty'),
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'is_ring': (UnaryPredicate, 'is_ring'),
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'is_simple': (UnaryPredicate, 'is_simple'),
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'is_valid': (UnaryPredicate, 'is_valid'),
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#
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'relate': (BinaryPredicate, 'relate'),
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'contains': (BinaryPredicate, 'contains'),
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'crosses': (BinaryPredicate, 'crosses'),
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'disjoint': (BinaryPredicate, 'disjoint'),
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'equals': (BinaryPredicate, 'equals'),
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'intersects': (BinaryPredicate, 'intersects'),
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'overlaps': (BinaryPredicate, 'overlaps'),
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'touches': (BinaryPredicate, 'touches'),
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'within': (BinaryPredicate, 'within'),
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'covers': (BinaryPredicate, 'covers'),
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'equals_exact': (BinaryPredicate, 'equals_exact'),
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'relate_pattern': (BinaryPredicate, 'relate_pattern'),
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# First pure Python implementation
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'is_ccw': (cga.is_ccw_impl, 'is_ccw'),
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}
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IMPL310 = {
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'simplify': (UnaryTopologicalOp, 'simplify'),
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'topology_preserve_simplify':
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(UnaryTopologicalOp, 'topology_preserve_simplify'),
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'prepared_disjoint': (BinaryPredicate, 'prepared_disjoint'),
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'prepared_touches': (BinaryPredicate, 'prepared_touches'),
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'prepared_crosses': (BinaryPredicate, 'prepared_crosses'),
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'prepared_within': (BinaryPredicate, 'prepared_within'),
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'prepared_overlaps': (BinaryPredicate, 'prepared_overlaps'),
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'prepared_intersects': (BinaryPredicate, 'prepared_intersects'),
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'prepared_contains': (BinaryPredicate, 'prepared_contains'),
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'prepared_contains_properly':
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(BinaryPredicate, 'prepared_contains_properly'),
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'prepared_covers': (BinaryPredicate, 'prepared_covers'),
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}
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IMPL311 = {
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}
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IMPL320 = {
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'parallel_offset': (UnaryTopologicalOp, 'parallel_offset'),
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'project_normalized': (ProjectOp, 'project_normalized'),
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'project': (ProjectOp, 'project'),
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'interpolate_normalized': (InterpolateOp, 'interpolate_normalized'),
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'interpolate': (InterpolateOp, 'interpolate'),
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'buffer_with_style': (UnaryTopologicalOp, 'buffer_with_style'),
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'hausdorff_distance': (BinaryRealProperty, 'hausdorff_distance'),
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}
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IMPL330 = {
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'is_closed': (UnaryPredicate, 'is_closed'),
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'buffer_with_params': (UnaryTopologicalOp, 'buffer_with_params'),
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}
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def impl_items(defs):
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return [(k, v[0](v[1])) for k, v in list(defs.items())]
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imp = GEOSImpl(dict(impl_items(IMPL300)))
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if lgeos.geos_version >= (3, 1, 0):
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imp.update(impl_items(IMPL310))
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if lgeos.geos_version >= (3, 1, 1):
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imp.update(impl_items(IMPL311))
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if lgeos.geos_version >= (3, 2, 0):
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imp.update(impl_items(IMPL320))
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if lgeos.geos_version >= (3, 3, 0):
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imp.update(impl_items(IMPL330))
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DefaultImplementation = imp
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