Fix: Enforce strict layout validation in Network space#3386
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Fix: Enforce strict layout validation in Network space#3386
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Performance benchmarks:
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quaquel
reviewed
Feb 26, 2026
mesa/discrete_space/network.py
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| # Create cells and gather KD-Tree data simultaneously | ||
| for node_id in self.G.nodes: | ||
| pos = np.array(node_positions.get(node_id)) | ||
| raw_pos = node_positions.get(node_id) |
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would it not make more sense to use:
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| raw_pos = node_positions.get(node_id) | |
| try: | |
| raw_pos = node_positions[node_id] | |
| except KeyError as e: | |
| raise SpaceException() from e |
quaquel
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Feb 26, 2026
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Looks fine to me with 1 question/suggestion.
quaquel
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Mar 2, 2026
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Summary
This PR fixes a bug where initializing a
Networkspace with an incomplete or emptylayoutdictionary resulted in a cryptic SciPyValueError. It introduces strict validation to explicitly catch missing node positions before spatial processing begins.Bug / Issue
Fixes #3385
When a
layoutdictionary was provided but was missing entries for certain node IDs,node_positions.get(node_id)returnedNone. ThisNonevalue was incorrectly wrapped into a NumPy array (np.array(None)), which bypassed the subsequentpos is not Noneguard. This invalid position was then passed toscipy.spatial.KDTree, causing a crash with the cryptic error.Implementation
__init__method inmesa/discrete_space/network.py. Extracted the position lookup (raw_pos = node_positions.get(node_id)) and added an explicitNonecheck before NumPy conversion. If a node is missing from the layout, the initialization now immediately halts and raises aSpaceExceptionwith a clear, Mesa-specific error message detailing the exact missing Node ID.if pos is not None:guard later in the loop since positions are now strictly validated.Testing
test_network_missing_layout_nodeintests/discrete_space/test_discrete_space.py.layout={}) and a partially missing layout both correctly raise the expectedSpaceException.Additional Notes
As discussed in the issue thread with the maintainers, this strict validation approach was chosen over silently falling back to a purely topological network mode. This prevents masking potential bugs in the user's data generation code where they might mistakenly expect spatial queries to work for dropped nodes.