feat: added create_famous_graph() and eperimented with string handling

Author: ntamas

src/codegen/types.yaml

@@ -29,6 +29,10 @@ DOUBLE:
 
 CSTRING:
   PY_TYPE: str
+  INCONV:
+    IN: '%C% = %I%.encode("utf-8")'
+    OUT: "%C% = c_char_p()"
+  OUTCONV: '%I% = %C%.value.decode("utf-8", "replace")'
 
 VECTOR:
   PY_TYPE: Iterable[float]

src/igraph_ctypes/_internal/functions.py

@@ -655,11 +655,11 @@ def kautz(m: int, n: int) -> _Graph:
     return graph
 
 
-def famous(name: str = "") -> _Graph:
+def famous(name: str) -> _Graph:
     """Type-annotated wrapper for ``igraph_famous``."""
     # Prepare input arguments
     c_graph = _Graph()
-    c_name = name
+    c_name = name.encode("utf-8")
 
     # Call wrapped function
     igraph_famous(c_graph, c_name)
@@ -5844,7 +5844,7 @@ def vertex_path_from_edge_path(graph: _Graph, start: VertexLike, edge_path: Iter
 def version() -> Tuple[str, int, int, int]:
     """Type-annotated wrapper for ``igraph_version``."""
     # Prepare input arguments
-    c_version_string = None
+    c_version_string = c_char_p()
     c_major = c_int()
     c_minor = c_int()
     c_subminor = c_int()
@@ -5853,7 +5853,7 @@ def version() -> Tuple[str, int, int, int]:
     igraph_version(c_version_string, c_major, c_minor, c_subminor)
 
     # Prepare output arguments
-    version_string = c_version_string.value
+    version_string = c_version_string.value.decode("utf-8", "replace")
     major = c_major.value
     minor = c_minor.value
     subminor = c_subminor.value

src/igraph_ctypes/constructors.py

@@ -1,7 +1,7 @@
 from typing import Iterable
 
 from .graph import Graph
-from ._internal.functions import create
+from ._internal.functions import create, famous
 
 __all__ = ("create_empty_graph", "create_graph_from_edge_list")
 
@@ -16,6 +16,18 @@ def create_empty_graph(n: int, directed: bool = False) -> Graph:
     return Graph(n, directed)
 
 
+def create_famous_graph(name: str) -> Graph:
+    """Creates one of the "famous" graphs embedded into igraph by name.
+
+    See the documentation of the ``igraph_famous()`` function in igraph's C core
+    for a list of names accepted by this function.
+
+    Parameters:
+        name: the name of the graph to construct
+    """
+    return Graph(_wrap=famous(name))
+
+
 def create_graph_from_edge_list(
     edges: Iterable[int], n: int = 0, directed: bool = False
 ) -> Graph:

test/test_constructors.py

@@ -2,7 +2,15 @@
 
 from numpy import array, ndarray
 
-from igraph_ctypes.constructors import create_graph_from_edge_list
+from igraph_ctypes.constructors import create_famous_graph, create_graph_from_edge_list
+
+
+def test_create_famous_graph():
+    g = create_famous_graph("zachary")
+    assert not g.is_directed() and g.vcount() == 34 and g.ecount() == 78
+
+    g = create_famous_graph("petersen")
+    assert not g.is_directed() and g.vcount() == 10 and g.ecount() == 15
 
 
 @pytest.mark.parametrize(

test/test_misc.py

@@ -0,0 +1,9 @@
+from igraph_ctypes._internal.functions import version
+
+
+def test_version():
+    version_str, major, minor, patch = version()
+    assert major >= 0 and major <= 255
+    assert minor >= (10 if major == 0 else 0) and minor <= 255
+    assert patch >= 0 and patch <= 255
+    assert version_str.startswith(f"{major}.{minor}.{patch}")