BUG: Mermaid nodes with spaces in name (#7835)

* standardize mermaid node names

* add test with space in variable name

* remove use of fixture

* use the "when in doubt, cast" strategy

Author: williambdean

pymc/model_graph.py

@@ -795,36 +795,42 @@ def model_to_graphviz(
     )
 
 
+def _create_mermaid_node_name(name: str) -> str:
+    return name.replace(":", "_").replace(" ", "_")
+
+
 def _build_mermaid_node(node: NodeInfo) -> list[str]:
     var = node.var
     node_type = node.node_type
+    name = cast(str, var.name)
+    node_name = _create_mermaid_node_name(name)
     if node_type == NodeType.DATA:
         return [
-            f"{var.name}[{var.name} ~ Data]",
-            f"{var.name}@{{ shape: db }}",
+            f"{node_name}[{var.name} ~ Data]",
+            f"{node_name}@{{ shape: db }}",
         ]
     elif node_type == NodeType.OBSERVED_RV:
         return [
-            f"{var.name}([{var.name} ~ {random_variable_symbol(var)}])",
-            f"{var.name}@{{ shape: rounded }}",
-            f"style {var.name} fill:#757575",
+            f"{node_name}([{name} ~ {random_variable_symbol(var)}])",
+            f"{node_name}@{{ shape: rounded }}",
+            f"style {node_name} fill:#757575",
         ]
 
     elif node_type == NodeType.FREE_RV:
         return [
-            f"{var.name}([{var.name} ~ {random_variable_symbol(var)}])",
-            f"{var.name}@{{ shape: rounded }}",
+            f"{node_name}([{name} ~ {random_variable_symbol(var)}])",
+            f"{node_name}@{{ shape: rounded }}",
         ]
     elif node_type == NodeType.DETERMINISTIC:
         return [
-            f"{var.name}([{var.name} ~ Deterministic])",
-            f"{var.name}@{{ shape: rect }}",
+            f"{node_name}([{name} ~ Deterministic])",
+            f"{node_name}@{{ shape: rect }}",
         ]
     elif node_type == NodeType.POTENTIAL:
         return [
-            f"{var.name}([{var.name} ~ Potential])",
-            f"{var.name}@{{ shape: diam }}",
-            f"style {var.name} fill:#f0f0f0",
+            f"{node_name}([{name} ~ Potential])",
+            f"{node_name}@{{ shape: diam }}",
+            f"style {node_name} fill:#f0f0f0",
         ]
 
     return []
@@ -842,8 +848,8 @@ def _build_mermaid_edges(edges) -> list[str]:
     """Return a list of Mermaid edge definitions."""
     edge_lines = []
     for child, parent in edges:
-        child_id = str(child).replace(":", "_")
-        parent_id = str(parent).replace(":", "_")
+        child_id = _create_mermaid_node_name(child)
+        parent_id = _create_mermaid_node_name(parent)
         edge_lines.append(f"{parent_id} --> {child_id}")
     return edge_lines
 

tests/test_model_graph.py

@@ -652,3 +652,20 @@ def test_model_to_mermaid(simple_model):
     %% Plates:
     """)
     assert model_to_mermaid(simple_model) == expected_mermaid_string.strip()
+
+
+def test_model_to_mermaid_with_variable_with_space():
+    with pm.Model() as variable_with_space:
+        pm.Normal("plant growth")
+
+    expected_mermaid_string = dedent("""
+    graph TD
+    %% Nodes:
+    plant_growth([plant growth ~ Normal])
+    plant_growth@{ shape: rounded }
+
+    %% Edges:
+
+    %% Plates:
+    """)
+    assert model_to_mermaid(variable_with_space) == expected_mermaid_string.strip()