Add exception specifically for graph isomorphism

CHANGELOG.md

@@ -16,6 +16,10 @@ Contributors:    @RMeli
 
 * Support for more types of node properties (including strings) with `graph-tool` [PR #64 | @RMeli]
 
+### Changed
+
+* `ValueError` exception into `NonIsomorphicGraphs(ValueError)` exception [PR #65 | @RMeli]
+
 ### Added
 
 * Warning for disconnected graphs [PR #61| @RMeli]

spyrmsd/exceptions.py

@@ -0,0 +1,6 @@
+class NonIsomorphicGraphs(ValueError):
+    """
+    Raised when graphs are not isomorphic
+    """
+
+    pass

spyrmsd/graphs/gt.py

@@ -5,6 +5,7 @@
 import numpy as np
 from graph_tool import generation, topology
 
+from spyrmsd.exceptions import NonIsomorphicGraphs
 from spyrmsd.graphs._common import (
     error_non_isomorphic_graphs,
     warn_disconnected_graph,
@@ -27,6 +28,11 @@ def _c_type(numpy_dtype):
     str
         C type
 
+    Raises
+    ------
+    ValueError
+        If the data type is not supported
+
     Notes
     -----
     https://graph-tool.skewed.de/static/doc/quickstart.html#sec-property-maps
@@ -113,7 +119,7 @@ def match_graphs(G1, G2) -> List[Tuple[List[int], List[int]]]:
 
     Raises
     ------
-    ValueError
+    NonIsomorphicGraphs
         If the graphs `G1` and `G2` are not isomorphic
     """
 
@@ -134,8 +140,7 @@ def match_graphs(G1, G2) -> List[Tuple[List[int], List[int]]]:
 
     # Check if graphs are actually isomorphic
     if len(maps) == 0:
-        # TODO: Create a new exception
-        raise ValueError(error_non_isomorphic_graphs)
+        raise NonIsomorphicGraphs(error_non_isomorphic_graphs)
 
     n = num_vertices(G1)
 

spyrmsd/graphs/nx.py

@@ -4,6 +4,7 @@
 import networkx as nx
 import numpy as np
 
+from spyrmsd.exceptions import NonIsomorphicGraphs
 from spyrmsd.graphs._common import (
     error_non_isomorphic_graphs,
     warn_disconnected_graph,
@@ -65,7 +66,7 @@ def match_graphs(G1, G2) -> List[Tuple[List[int], List[int]]]:
 
     Raises
     ------
-    ValueError
+    NonIsomorphicGraphs
         If the graphs `G1` and `G2` are not isomorphic
     """
 
@@ -92,8 +93,7 @@ def match_aprops(node1, node2):
 
     # Check if graphs are actually isomorphic
     if not GM.is_isomorphic():
-        # TODO: Create a new exception
-        raise ValueError(error_non_isomorphic_graphs)
+        raise NonIsomorphicGraphs(error_non_isomorphic_graphs)
 
     return [
         (list(isomorphism.keys()), list(isomorphism.values()))

tests/test_graph.py

@@ -2,6 +2,7 @@
 import pytest
 
 from spyrmsd import constants, graph, io, molecule
+from spyrmsd.exceptions import NonIsomorphicGraphs
 from tests import molecules
 
 
@@ -126,9 +127,9 @@ def test_match_graphs_isomorphic(G1, G2) -> None:
 )
 def test_match_graphs_not_isomorphic(G1, G2) -> None:
 
-    with pytest.raises(ValueError, match="Graphs are not isomorphic."), pytest.warns(
-        UserWarning, match="No atomic number information stored on nodes."
-    ):
+    with pytest.raises(
+        NonIsomorphicGraphs, match="Graphs are not isomorphic."
+    ), pytest.warns(UserWarning, match="No atomic number information stored on nodes."):
         graph.match_graphs(G1, G2)