Add node-specific tolerances to intersection consolidation

osmnx/simplification.py

@@ -446,7 +446,7 @@
 def consolidate_intersections(
  G: nx.MultiDiGraph,
  *,
- tolerance: float = 10,
+ tolerance: float | dict[int, float] = 10,
  rebuild_graph: bool = True,
  dead_ends: bool = False,
  reconnect_edges: bool = True,
@@ -463,6 +463,11 @@
  Note `tolerance` represents a per-node buffering radius: for example, to
  consolidate nodes within 10 meters of each other, use `tolerance=5`.
 
+ It's also possible to specify difference tolerances for each node. This can
+ be done by adding an attribute to each node with contains the tolerance, and
+ passing the name of that argument as tolerance_attribute argument. If a node
+ does not have a value in the tolerance_attribute, the default tolerance is used.
+
  When `rebuild_graph` is False, it uses a purely geometric (and relatively
  fast) algorithm to identify "geometrically close" nodes, merge them, and
  return the merged intersections' centroids. When `rebuild_graph` is True,
@@ -487,7 +492,8 @@
  A projected graph.
  tolerance
  Nodes are buffered to this distance (in graph's geometry's units) and
- subsequent overlaps are dissolved into a single node.
+ subsequent overlaps are dissolved into a single node. Can be a float
+ value or a dictionary mapping node IDs to individual tolerance values.
  rebuild_graph
  If True, consolidate the nodes topologically, rebuild the graph, and
  return as MultiDiGraph. Otherwise, consolidate the nodes geometrically
@@ -547,7 +553,10 @@
  return _merge_nodes_geometric(G, tolerance).centroid
 
 
-def _merge_nodes_geometric(G: nx.MultiDiGraph, tolerance: float) -> gpd.GeoSeries:
+def _merge_nodes_geometric(
+ G: nx.MultiDiGraph,
+ tolerance: float | dict[int, float],
+) -> gpd.GeoSeries:
  """
  Geometrically merge nodes within some distance of each other.
 
@@ -558,14 +567,25 @@
  tolerance
  Buffer nodes to this distance (in graph's geometry's units) then merge
  overlapping polygons into a single polygon via unary union operation.
+ Can be a float value or a dictionary mapping node IDs to individual
+ tolerance values.
 
  Returns
  -------
  merged
  The merged overlapping polygons of the buffered nodes.
  """
- # buffer nodes GeoSeries then get unary union to merge overlaps
- merged = convert.graph_to_gdfs(G, edges=False)["geometry"].buffer(tolerance).unary_union
+ gdf_nodes = convert.graph_to_gdfs(G, edges=False)
+
+ if isinstance(tolerance, dict):
+ # Map tolerances to node IDs, using NaN for nodes not in the dictionary, and fill NaN with zero
+ buffer_distances = gdf_nodes.index.to_series().map(tolerance).fillna(0)
+ else:
+ # Use the default tolerance for all nodes
+ buffer_distances = tolerance
+
+ # Buffer nodes to the specified distances and merge them
+ merged = gdf_nodes.geometry.buffer(distance=buffer_distances).unary_union
 
  # if only a single node results, make it iterable to convert to GeoSeries
  merged = MultiPolygon([merged]) if isinstance(merged, Polygon) else merged
@@ -574,7 +594,7 @@
 
 def _consolidate_intersections_rebuild_graph( # noqa: C901,PLR0912,PLR0915
  G: nx.MultiDiGraph,
- tolerance: float,
+ tolerance: float | dict[int, float],
  reconnect_edges: bool, # noqa: FBT001
  node_attr_aggs: dict[str, Any] | None,
 ) -> nx.MultiDiGraph:
@@ -599,7 +619,8 @@
  A projected graph.
  tolerance
  Nodes are buffered to this distance (in graph's geometry's units) and
- subsequent overlaps are dissolved into a single node.
+ subsequent overlaps are dissolved into a single node. Can be a float
+ value or a dictionary mapping node IDs to individual tolerance values.
  reconnect_edges
  If True, reconnect edges (and their geometries) to the consolidated
  nodes in rebuilt graph, and update the edge length attributes. If
@@ -625,7 +646,9 @@
  # STEP 1
  # buffer nodes to passed-in distance and merge overlaps. turn merged nodes
  # into gdf and get centroids of each cluster as x, y
- node_clusters = gpd.GeoDataFrame(geometry=_merge_nodes_geometric(G, tolerance))
+ node_clusters = gpd.GeoDataFrame(
+ geometry=_merge_nodes_geometric(G, tolerance),
+ )
  centroids = node_clusters.centroid
  node_clusters["x"] = centroids.x
  node_clusters["y"] = centroids.y