def test_hashmap_can_set_an_object_by_key(self):
map = HashMap(10, hash, equal)
key = {'hash': 1}
map.set(key, 42)
self.assertEqual(map.get(key), 42)
def test_hashmap_when_a_hash_collision_occurs_get_checks_that_the_keys_are_equal(
self):
map = HashMap(10, hash, equal)
key_1 = {'hash': 1}
key_2 = {'hash': 1}
key_3 = {'hash': 1}
map.set(key_1, 'A')
map.set(key_2, 'B')
self.assertEqual(map.get(key_1), 'A')
self.assertEqual(map.get(key_2), 'B')
self.assertEqual(map.get(key_3), None)
def test_hashmap_when_a_hash_collision_occurs_get_checks_that_the_keys_are_equal(
self,
):
map = HashMap(10, hash, equal)
key_1 = {"hash": 1}
key_2 = {"hash": 1}
key_3 = {"hash": 1}
map.set(key_1, "A")
map.set(key_2, "B")
self.assertEqual(map.get(key_1), "A")
self.assertEqual(map.get(key_2), "B")
self.assertEqual(map.get(key_3), None)
def test_hashmap_the_hash_function_must_return_a_nonnegative_integer_but_can_be_greater_than_size(
self):
map = HashMap(10, hash, equal)
key = {'hash': 11}
self.assertEqual(map.get(key), None)
self.assertEqual(map.set(key, 42), 42)
self.assertEqual(map.get(key), 42)
def test_hashmap_set_throws_an_error_when_full(self):
# minimum size of 16
map = HashMap(0, hash, equal)
keys = list()
for i in range(16):
keys.append({'hash': i})
map.set(keys[i], True)
# replacing is okay
for i in range(16):
map.set(keys[i], True)
with self.assertRaises(ValueError):
map.set({'hash': 16}, True)
def test_hashmap_set_returns_the_set_value(self):
map = HashMap(10, hash, equal)
key = {'hash': 1}
self.assertEqual(map.set(key, 42), 42)
class Dedup(object):
"""
Given a cut topology, combines duplicate arcs.
"""
def __init__(self):
pass
def __call__(self, topology, *args, **kwargs):
self.coordinates = topology["coordinates"]
self.lines = topology["lines"].copy()
self.rings = topology["rings"].copy()
self.arc_count = len(self.lines) + len(self.rings)
topology.pop("lines", None)
topology.pop("rings", None)
for l in self.lines:
line = l
while line.get("next", False):
self.arc_count += 1
line = line["next"]
for r in self.rings:
ring = r
while ring.get("next", False):
self.arc_count += 1
ring = ring["next"]
self.arcs_by_end = HashMap(self.arc_count * 2 * 1.4, hash_point,
equal_point)
self.arcs = list()
for l in self.lines:
line = l
while line:
self.dedup_line(line)
line = line.get("next", False)
for r in self.rings:
ring = r
# arc is no longer closed
if ring.get("next", False):
while ring:
self.dedup_line(ring)
ring = ring.get("next", False)
else:
self.dedup_ring(ring)
topology["arcs"] = self.arcs.copy()
return topology
def dedup_line(self, arc):
# Does this arc match an existing arc in order?
start_point = self.coordinates[arc[0]]
start_arcs = self.arcs_by_end.get(start_point)
if start_arcs:
for start_arc in start_arcs:
if self.equal_line(start_arc, arc):
arc[0] = start_arc[0]
arc[1] = start_arc[1]
return
# Does this arc match an existing arc in reverse order?
end_point = self.coordinates[arc[1]]
end_arcs = self.arcs_by_end.get(end_point)
if end_arcs:
for end_arc in end_arcs:
if self.reverse_equal_line(end_arc, arc):
arc[0] = end_arc[1]
arc[1] = end_arc[0]
return
if start_arcs:
start_arcs.append(arc)
else:
self.arcs_by_end.set(start_point, [arc])
if end_arcs:
end_arcs.append(arc)
else:
self.arcs_by_end.set(end_point, [arc])
self.arcs.append(arc)
def dedup_ring(self, arc):
# Does this arc match an existing line in order, or reverse order?
# Rings are closed, so their start point and end point is the same.
end_point = self.coordinates[arc[0]]
end_arcs = self.arcs_by_end.get(end_point)
if end_arcs:
for end_arc in end_arcs:
if self.equal_ring(end_arc, arc):
arc[0] = end_arc[0]
arc[1] = end_arc[1]
return
if self.reverse_equal_ring(end_arc, arc):
arc[0] = end_arc[1]
arc[1] = end_arc[0]
return
# Otherwise, does this arc match an existing ring in order, or reverse order?
end_point = self.coordinates[arc[0] + self.find_minimum_offset(arc)]
end_arcs = self.arcs_by_end.get(end_point)
if end_arcs:
for end_arc in end_arcs:
if self.equal_ring(end_arc, arc):
arc[0] = end_arc[0]
arc[1] = end_arc[1]
return
if self.reverse_equal_ring(end_arc, arc):
arc[0] = end_arc[1]
arc[1] = end_arc[0]
return
if end_arcs:
end_arcs.append(arc)
else:
self.arcs_by_end.set(end_point, [arc])
self.arcs.append(arc)
def equal_line(self, arc_a, arc_b):
i_a, j_a = arc_a[0], arc_a[1]
i_b, j_b = arc_b[0], arc_b[1]
if i_a - j_a != i_b - j_b:
return False
while i_a <= j_a:
if not equal_point(self.coordinates[i_a], self.coordinates[i_b]):
return False
else:
i_a += 1
i_b += 1
return True
def reverse_equal_line(self, arc_a, arc_b):
i_a, j_a = arc_a[0], arc_a[1]
i_b, j_b = arc_b[0], arc_b[1]
if i_a - j_a != i_b - j_b:
return False
while i_a <= j_a:
if not equal_point(self.coordinates[i_a], self.coordinates[j_b]):
return False
else:
i_a += 1
j_b -= 1
return True
def equal_ring(self, arc_a, arc_b):
i_a, j_a = arc_a[0], arc_a[1]
i_b, j_b = arc_b[0], arc_b[1]
n = j_a - i_a
if n != j_b - i_b:
return False
k_a = self.find_minimum_offset(arc_a)
k_b = self.find_minimum_offset(arc_b)
for i in range(n):
if not equal_point(
self.coordinates[i_a + (i + k_a) % n],
self.coordinates[i_b + (i + k_b) % n],
):
return False
return True
def reverse_equal_ring(self, arc_a, arc_b):
i_a, j_a = arc_a[0], arc_a[1]
i_b, j_b = arc_b[0], arc_b[1]
n = j_a - i_a
if n != j_b - i_b:
return False
k_a = self.find_minimum_offset(arc_a)
k_b = n - self.find_minimum_offset(arc_b)
for i in range(n):
if not equal_point(
self.coordinates[i_a + (i + k_a) % n],
self.coordinates[j_b - (i + k_b) % n],
):
return False
return True
def find_minimum_offset(self, arc):
# Rings are rotated to a consistent, but arbitrary, start point.
# This is necessary to detect when a ring and a rotated copy are dupes.
start, end = arc[0], arc[1]
mid = start
minimum = mid
minimum_point = self.coordinates[mid]
mid += 1
while mid < end:
point = self.coordinates[mid]
if (point[0] < minimum_point[0] or point[0] == minimum_point[0]
and point[1] < minimum_point[1]):
minimum = mid
minimum_point = point
mid += 1
return minimum - start
class Topology(object):
"""
Constructs the TopoJSON Topology for the specified hash of features.
Each object in the specified hash must be a GeoJSON object,
meaning FeatureCollection, a Feature or a geometry object.
"""
def __init__(self):
self.bounding_box = bounds.BoundingBox()
self.cut = cut.Cut()
self.dedup = dedup.Dedup()
self.delta = delta.Delta()
self.extract = extract.Extract()
self.geometry = geometry.Geometry()
self.prequantize = prequantize.Prequantize()
def __call__(self, objects, quantization=-1):
self.index_geometry_type = {
"GeometryCollection": self._geometry_collection_call,
"LineString": self._line_string_call,
"MultiLineString": self._multi_line_string_call,
"Polygon": self._polygon_call,
"MultiPolygon": self._multi_polygon_call,
}
objects = self.geometry(objects)
self.bbox = self.bounding_box(objects)
self.transform = (
quantization > 0
and self.bbox
and self.prequantize(objects, self.bbox, quantization)
)
self.topology = self.dedup(self.cut(self.extract(objects)))
self.coordinates = self.topology["coordinates"]
self.index_by_arc = HashMap(
len(self.topology["arcs"]) * 1.4, self.hash_arc, self.equal_arc
)
objects = self.topology["objects"]
if self.bbox is not None:
self.topology["bbox"] = self.bbox
self.topology["arcs"] = list(
map(
lambda arc, i: self._slice(arc, i),
self.topology["arcs"],
range(len(self.topology["arcs"])),
)
)
self.topology.pop("coordinates", None)
self.coordinates = None
for k in objects:
self.index_geometry(objects[k])
if self.transform:
self.topology["transform"] = self.transform
self.topology["arcs"] = self.delta(self.topology["arcs"])
return self.topology
def _slice(self, arc, i):
self.index_by_arc.set(arc, i)
return self.coordinates[arc[0] : arc[1] + 1]
def _geometry_collection_call(self, o):
list(map(self.index_geometry, o["geometries"]))
def _line_string_call(self, o):
o["arcs"] = self.index_arcs(o["arcs"])
def _multi_line_string_call(self, o):
o["arcs"] = list(map(self.index_arcs, o["arcs"]))
def _polygon_call(self, o):
o["arcs"] = list(map(self.index_arcs, o["arcs"]))
def _multi_polygon_call(self, o):
o["arcs"] = list(map(self.index_multi_arcs, o["arcs"]))
def index_geometry(self, geometry):
function = self.index_geometry_type.get(geometry["type"], None)
if geometry and function:
function(geometry)
def index_arcs(self, arc):
indexes = list()
while arc:
index = self.index_by_arc.get(arc)
indexes.append(index if arc[0] < arc[1] else ~index)
arc = arc.get("next", False)
return indexes
def index_multi_arcs(self, arcs):
return list(map(self.index_arcs, arcs))
@staticmethod
def hash_arc(arc):
i, j = arc[0], arc[1]
if j < i:
t = i
i = j
j = t
return i + 31 * j
@staticmethod
def equal_arc(arc_a, arc_b):
i_a, j_a = arc_a[0], arc_a[1]
i_b, j_b = arc_b[0], arc_b[1]
if j_a < i_a:
t = i_a
i_a = j_a
j_a = t
if j_b < i_b:
t = i_b
i_b = j_b
j_b = t
return i_a == i_b and j_a == j_b