Update get_num_{vertices,edges} for single-GPU PropertyGraph:

- add `include_edge_data=True` keyword to `get_num_vertices`
- improved docstrings of `get_num_vertices` and `get_num_edges`
- change default type name to `""`
- remove `num_vertices` and `num_edges` properties
- use `series.value_counts` to compute counts of types (assuming types are low cardinality)
- add and update tests
- copy `pG.num_vertices_with_properties` tests from rapidsai#2419

MG is not quite finished yet.

python/cugraph/cugraph/structure/property_graph.py

@@ -65,6 +65,7 @@ class EXPERIMENTAL__PropertyGraph:
  edge_id_col_name = "_EDGE_ID_"
  vertex_id_col_name = "_VERTEX_ID_"
  weight_col_name = "_WEIGHT_"
+ _default_type_name = ""
 
  def __init__(self):
  # The dataframe containing the properties for each vertex.
@@ -135,30 +136,10 @@ def __init__(self):
 
  # Cached property values
  self.__num_vertices = None
+ self.__vertex_type_value_counts = None
+ self.__edge_type_value_counts = None
 
  # PropertyGraph read-only attributes
- @property
- def num_vertices(self):
- if self.__num_vertices is not None:
- return self.__num_vertices
-
- self.__num_vertices = 0
- vert_sers = self.__get_all_vertices_series()
- if vert_sers:
- if self.__series_type is cudf.Series:
- self.__num_vertices = cudf.concat(vert_sers).nunique()
- else:
- self.__num_vertices = pd.concat(vert_sers).nunique()
-
- return self.__num_vertices
-
- @property
- def num_edges(self):
- if self.__edge_prop_dataframe is not None:
- return len(self.__edge_prop_dataframe)
- else:
- return 0
-
  @property
  def edges(self):
  if self.__edge_prop_dataframe is not None:
@@ -195,45 +176,99 @@ def _vertex_prop_dataframe(self):
  def _edge_prop_dataframe(self):
  return self.__edge_prop_dataframe
 
- def get_num_vertices(self, type=None):
- """Return the number of vertices of a given type.
+ @property
+ def _vertex_type_value_counts(self):
+ if self.__vertex_prop_dataframe is None:
+ return
+ if self.__vertex_type_value_counts is None:
+ # Types should all be strings; what should we do if we see NaN?
+ self.__vertex_type_value_counts = (
+ self.__vertex_prop_dataframe[self.type_col_name]
+ .value_counts(sort=False, dropna=False)
+ )
+ return self.__vertex_type_value_counts
 
- If type is None, return the total number of vertices.
+ @property
+ def _edge_type_value_counts(self):
+ if self.__edge_prop_dataframe is None:
+ return
+ if self.__edge_type_value_counts is None:
+ # Types should all be strings; what should we do if we see NaN?
+ self.__edge_type_value_counts = (
+ self.__edge_prop_dataframe[self.type_col_name]
+ .value_counts(sort=False, dropna=False)
+ )
+ return self.__edge_type_value_counts
+
+ def get_num_vertices(self, type=None, *, include_edge_data=True):
+ """Return the number of all vertices or vertices of a given type.
 
- Vertex types are set by using the `type_name` argument in
- `add_vertex_data`.
+ Parameters
+ ----------
+ type : string, optional
+ If type is None (the default), return the total number of vertices,
+ otherwise return the number of vertices of the specified type.
+ include_edge_data : bool (default True)
+ If True, include vertices that were added in vertex and edge data.
+ If False, only include vertices that were added in vertex data.
+ Note that vertices that only exist in edge data are assumed to have
+ the default type.
 
  See Also
  --------
- PropertyGraph.num_vertices
  PropertyGraph.get_num_edges
  """
  if type is None:
- return self.num_vertices
+ if not include_edge_data:
+ if self.__vertex_prop_dataframe is None:
+ return 0
+ return len(self.__vertex_prop_dataframe)
+ if self.__num_vertices is not None:
+ return self.__num_vertices
+ self.__num_vertices = 0
+ vert_sers = self.__get_all_vertices_series()
+ if vert_sers:
+ if self.__series_type is cudf.Series:
+ self.__num_vertices = cudf.concat(vert_sers).nunique()
+ else:
+ self.__num_vertices = pd.concat(vert_sers).nunique()
+ return self.__num_vertices
+ value_counts = self._vertex_type_value_counts
+ if type == self._default_type_name and include_edge_data:
+ # The default type, "", can refer to both vertex and edge data
+ if self.__vertex_prop_dataframe is None:
+ return self.get_num_vertices()
+ return (
+ self.get_num_vertices()
+ - len(self.__vertex_prop_dataframe)
+ + (value_counts[type] if type in value_counts else 0)
+ )
  if self.__vertex_prop_dataframe is None:
  return 0
- # This counts duplicates
- return (self.__vertex_prop_dataframe[self.type_col_name] == type).sum()
+ return value_counts[type] if type in value_counts else 0
 
  def get_num_edges(self, type=None):
- """Return the number of edges of a given type.
-
- If type is None, return the total number of edges.
+ """Return the number of all edges or edges of a given type.
 
- Edge types are set by using the `type_name` argument in
- `add_edge_data`.
+ Parameters
+ ----------
+ type : string, optional
+ If type is None (the default), return the total number of edges,
+ otherwise return the number of edges of the specified type.
 
  See Also
  --------
- PropertyGraph.num_edges
  PropertyGraph.get_num_vertices
  """
  if type is None:
- return self.num_edges
+ if self.__edge_prop_dataframe is not None:
+ return len(self.__edge_prop_dataframe)
+ else:
+ return 0
  if self.__edge_prop_dataframe is None:
  return 0
- # This counts duplicates
- return (self.__edge_prop_dataframe[self.type_col_name] == type).sum()
+ value_counts = self._edge_type_value_counts
+ return value_counts[type] if type in value_counts else 0
 
  def get_vertices(self, selection=None):
  """
@@ -274,7 +309,7 @@ def add_vertex_data(self,
  The name to be assigned to the type of property being added. For
  example, if dataframe contains data about users, type_name might be
  "users". If not specified, the type of properties will be added as
- None or NA
+ the empty string, "".
  property_columns : list of strings
  List of column names in dataframe to be added as properties. All
  other columns in dataframe will be ignored. If not specified, all
@@ -297,6 +332,8 @@ def add_vertex_data(self,
  if (type_name is not None) and not(isinstance(type_name, str)):
  raise TypeError("type_name must be a string, got: "
  f"{type(type_name)}")
+ if type_name is None:
+ type_name = self._default_type_name
  if property_columns:
  if type(property_columns) is not list:
  raise TypeError("property_columns must be a list, got: "
@@ -321,6 +358,7 @@ def add_vertex_data(self,
  # Clear the cached value for num_vertices since more could be added in
  # this method.
  self.__num_vertices = None
+ self.__vertex_type_value_counts = None # Could update instead
 
  # Initialize the __vertex_prop_dataframe if necessary using the same
  # type as the incoming dataframe.
@@ -391,7 +429,7 @@ def add_edge_data(self,
  The name to be assigned to the type of property being added. For
  example, if dataframe contains data about transactions, type_name
  might be "transactions". If not specified, the type of properties
- will be added as None or NA
+ will be added as the empty string "".
  property_columns : list of strings
  List of column names in dataframe to be added as properties. All
  other columns in dataframe will be ignored. If not specified, all
@@ -418,6 +456,8 @@ def add_edge_data(self,
  if (type_name is not None) and not(isinstance(type_name, str)):
  raise TypeError("type_name must be a string, got: "
  f"{type(type_name)}")
+ if type_name is None:
+ type_name = self._default_type_name
  if property_columns:
  if type(property_columns) is not list:
  raise TypeError("property_columns must be a list, got: "
@@ -442,6 +482,7 @@ def add_edge_data(self,
  # Clear the cached value for num_vertices since more could be added in
  # this method.
  self.__num_vertices = None
+ self.__edge_type_value_counts = None # Could update instead
 
  default_edge_columns = [self.src_col_name,
  self.dst_col_name,