Fix #840: Add GraphML serializer

docs/source/api/serialization.rst

@@ -8,5 +8,7 @@ Serialization
 
    rustworkx.node_link_json
    rustworkx.read_graphml
+   rustworkx.read_graphml_with_keys
+   rustworkx.write_graphml
    rustworkx.from_node_link_json_file
    rustworkx.parse_node_link_json

releasenotes/notes/write_graphml-624c10b6f7592ee1.yaml

@@ -0,0 +1,13 @@
+---
+features:
+  - |
+    Added a new function :func:`~rustworkx.write_graphml` that writes
+    a list of rustworkx graph objects to a file in GraphML format.
+  - |
+    Added a new function :func:`~rustworkx.read_graphml_with_keys`
+    that reads a GraphML file and returns the list of defined keys
+    along with the list of rustworkx graph objects.
+other:
+  - |
+    When graphs read with :func:`~rustworkx.read_graphml` include IDs,
+    these IDs are now stored in the graph attributes.

rustworkx/__init__.pyi

@@ -163,6 +163,8 @@ from .rustworkx import directed_barabasi_albert_graph as directed_barabasi_alber
 from .rustworkx import undirected_random_bipartite_graph as undirected_random_bipartite_graph
 from .rustworkx import directed_random_bipartite_graph as directed_random_bipartite_graph
 from .rustworkx import read_graphml as read_graphml
+from .rustworkx import read_graphml_with_keys as read_graphml_with_keys
+from .rustworkx import write_graphml as write_graphml
 from .rustworkx import digraph_node_link_json as digraph_node_link_json
 from .rustworkx import graph_node_link_json as graph_node_link_json
 from .rustworkx import from_node_link_json_file as from_node_link_json_file

rustworkx/rustworkx.pyi

@@ -68,6 +68,30 @@ class ColoringStrategy:
     Saturation: Any
     IndependentSet: Any
 
+@final
+class GraphMLDomain:
+    Node: GraphMLDomain
+    Edge: GraphMLDomain
+    Graph: GraphMLDomain
+    All: GraphMLDomain
+
+@final
+class GraphMLType:
+    Boolean: GraphMLType
+    Int: GraphMLType
+    Float: GraphMLType
+    Double: GraphMLType
+    String: GraphMLType
+    Long: GraphMLType
+
+@final
+class GraphMLKey:
+    id: str
+    domain: GraphMLDomain
+    name: str
+    ty: GraphMLType
+    default: Any
+
 # Cartesian product
 
 def digraph_cartesian_product(
@@ -680,11 +704,23 @@ def directed_random_bipartite_graph(
 
 # Read Write
 
+def read_graphml_with_keys(
+    path: str,
+    /,
+    compression: str | None = ...,
+) -> tuple[list[GraphMLKey], list[PyGraph | PyDiGraph]]: ...
 def read_graphml(
     path: str,
     /,
     compression: str | None = ...,
 ) -> list[PyGraph | PyDiGraph]: ...
+def write_graphml(
+    graphs: list[PyGraph | PyDiGraph],
+    keys: list[GraphMLKey],
+    path: str,
+    /,
+    compression: str | None = ...,
+) -> None: ...
 def digraph_node_link_json(
     graph: PyDiGraph[_S, _T],
     /,