Change default return type `PropertyGraph.extract_subgraph() -> cugra…

…ph.Graph(directed=True)` (#2460)

Fixes #2459

The tests already specify the use of directed graphs most places, so this required minimal changes.

Authors:
  - Erik Welch (https://github.com/eriknw)

Approvers:
  - Rick Ratzel (https://github.com/rlratzel)

URL: #2460

python/cugraph/cugraph/dask/structure/mg_property_graph.py

@@ -480,7 +480,7 @@ def select_edges(self, expr):
  edge_selection_series=selected_col)
 
  def extract_subgraph(self,
- create_using=cugraph.Graph,
+ create_using=None,
  selection=None,
  edge_weight_property=None,
  default_edge_weight=None,
@@ -494,12 +494,12 @@ def extract_subgraph(self,
 
  Parameters
  ----------
- create_using : cugraph Graph type or instance
+ create_using : cugraph Graph type or instance, optional
  Creates a Graph to return using the type specified. If an instance
  is specified, the type of the instance is used to construct the
  return Graph, and all relevant attributes set on the instance are
  copied to the return Graph (eg. directed). If not specified the
- returned Graph will be a cugraph.Graph instance.
+ returned Graph will be a directed cugraph.Graph instance.
  selection : PropertySelection
  A PropertySelection returned from one or more calls to
  select_vertices() and/or select_edges(), used for creating a Graph
@@ -576,6 +576,12 @@ def extract_subgraph(self,
  # values. Restore the original dtypes in the resulting edges df prior
  # to creating a Graph.
  self.__update_dataframe_dtypes(edges, self.__edge_prop_dtypes)
+
+ # Default create_using set here instead of function signature to
+ # prevent cugraph from running on import. This may help diagnose errors
+ if create_using is None:
+ create_using = cugraph.Graph(directed=True)
+
  return self.edge_props_to_graph(
  edges,
  create_using=create_using,

python/cugraph/cugraph/structure/property_graph.py

@@ -563,7 +563,7 @@ def select_edges(self, expr):
  edge_selection_series=selected_col)
 
  def extract_subgraph(self,
- create_using=cugraph.Graph,
+ create_using=None,
  selection=None,
  edge_weight_property=None,
  default_edge_weight=None,
@@ -577,12 +577,12 @@ def extract_subgraph(self,
 
  Parameters
  ----------
- create_using : cugraph Graph type or instance
+ create_using : cugraph Graph type or instance, optional
  Creates a Graph to return using the type specified. If an instance
  is specified, the type of the instance is used to construct the
  return Graph, and all relevant attributes set on the instance are
  copied to the return Graph (eg. directed). If not specified the
- returned Graph will be a cugraph.Graph instance.
+ returned Graph will be a directed cugraph.Graph instance.
  selection : PropertySelection
  A PropertySelection returned from one or more calls to
  select_vertices() and/or select_edges(), used for creating a Graph
@@ -661,6 +661,11 @@ def extract_subgraph(self,
  # to creating a Graph.
  edges = self.__update_dataframe_dtypes(edges, self.__edge_prop_dtypes)
 
+ # Default create_using set here instead of function signature to
+ # prevent cugraph from running on import. This may help diagnose errors
+ if create_using is None:
+ create_using = cugraph.Graph(directed=True)
+
  return self.edge_props_to_graph(
  edges,
  create_using=create_using,

python/cugraph/cugraph/tests/test_property_graph.py

@@ -755,6 +755,7 @@ def test_extract_subgraph_no_edges(dataset1_PropertyGraph):
 
  selection = pG.select_vertices("(_TYPE_=='merchants') & (merchant_id==86)")
  G = pG.extract_subgraph(selection=selection)
+ assert G.is_directed()
 
  assert len(G.edgelist.edgelist_df) == 0