def create_sub_graph(self, poi) -> cugraph.Graph:
"""
Create a subgraph of road nodes based on buffer distance
The subgraph is created using euclidean distance and
`cuspatial.points_in_spatial_window`. If buffers are not large enough to
include all nodes identified as important to that particular POI, it is
increased in size.
Parameters
----------
poi : namedtuple
Single POI created by `df.itertuples()`
Returns
-------
cugraph.Graph:
Graph object that is a subset of all road nodes
"""
buffer = max(poi.buffer, self.buffer)
while True:
node_subset = cuspatial.points_in_spatial_window(
min_x=poi.easting - buffer,
max_x=poi.easting + buffer,
min_y=poi.northing - buffer,
max_y=poi.northing + buffer,
xs=self.nodes["easting"],
ys=self.nodes["northing"],
)
node_subset = node_subset.merge(self.nodes,
left_on=["x", "y"],
right_on=["easting", "northing"
]).drop(["x", "y"],
axis=1)
sub_source = self.edges.merge(node_subset,
left_on="source",
right_on="node_id")
sub_target = self.edges.merge(node_subset,
left_on="target",
right_on="node_id")
sub_edges = sub_source.append(sub_target).drop_duplicates(
["source", "target"])
sub_graph = cugraph.Graph()
sub_graph.from_cudf_edgelist(
sub_edges,
source="source",
destination="target",
edge_attr=self.weights,
renumber=False,
)
pc_nodes = cudf.Series(poi.pc_node).isin(sub_graph.nodes()).sum()
poi_node = sub_graph.nodes().isin([poi.node_id]).sum()
# ensure all postcode nodes in + poi node
# don't incrase buffer for large pois lists
if poi_node & ((pc_nodes == len(poi.pc_node)) or
(len(self.pois) > 100_000)):
return sub_graph
buffer = buffer * 2
print(f"{poi.Index=}: increasing {buffer=}")
def test_pair():
result = cuspatial.points_in_spatial_window(-1.1, 1.1, -1.1, 1.1,
cudf.Series([0.0, 1.0]),
cudf.Series([1.0, 0.0]))
cudf.testing.assert_frame_equal(
result, cudf.DataFrame({
"x": [0.0, 1.0],
"y": [1.0, 0.0]
}))
def test_corners(coords):
x, y = coords
result = cuspatial.points_in_spatial_window(-1.1, 1.1, -1.1, 1.1,
cudf.Series([x]),
cudf.Series([y]))
cudf.testing.assert_frame_equal(result, cudf.DataFrame({
"x": [x],
"y": [y]
}))
def test_half():
result = cuspatial.points_in_spatial_window(
-2,
2,
-2,
2,
cudf.Series([-1.0, 1.0, 3.0, -3.0]),
cudf.Series([1.0, -1.0, 3.0, -3.0]),
)
print(result)
assert_eq(result, cudf.DataFrame({"x": [-1.0, 1.0], "y": [1.0, -1.0]}))
def test_zeros():
result = cuspatial.points_in_spatial_window( # noqa: F841
0, 0, 0, 0, cudf.Series([0.0]), cudf.Series([0.0]))
assert result.empty
def test_oob():
result = cuspatial.points_in_spatial_window(-1, 1, -1, 1,
cudf.Series([-2.0, 2.0]),
cudf.Series([2.0, -2.0]))
cudf.testing.assert_frame_equal(result, cudf.DataFrame({"x": [], "y": []}))
def test_centered():
result = cuspatial.points_in_spatial_window(-1, 1, -1, 1,
cudf.Series([0.0]),
cudf.Series([0.0]))
assert_eq(result, cudf.DataFrame({"x": [0.0], "y": [0.0]}))