removing obsolete line_graph()

python/dgl/generator/__init__.py

-"""Package for graph generators"""
-from __future__ import absolute_import
-
-from .line import *

python/dgl/generator/line.py

-"""Line graph generator."""
-from __future__ import absolute_import
-
-import networkx as nx
-import numpy as np
-
-from .. import backend as F
-from ..graph import DGLGraph
-from ..frame import FrameRef
-
-def line_graph(G, no_backtracking=False):
-    """Create the line graph that shares the underlying features.
-
-    The node features of the result line graph will share the edge features
-    of the given graph.
-
-    Parameters
-    ----------
-    G : DGLGraph
-        The input graph.
-    no_backtracking : bool
-        Whether the backtracking edges are included in the line graph.
-        If i~j and j~i are two edges in original graph G, then
-        (i,j)~(j,i) and (j,i)~(i,j) are the "backtracking" edges on
-        the line graph.
-    """
-    L = nx.DiGraph()
-    for eid, from_node in enumerate(G.edge_list):
-        L.add_node(from_node)
-        for to_node in G.edges(from_node[1]):
-            if no_backtracking and to_node[1] == from_node[0]:
-                continue
-            L.add_edge(from_node, to_node)
-    relabel_map = {}
-    for i, e in enumerate(G.edge_list):
-        relabel_map[e] = i
-    nx.relabel.relabel_nodes(L, relabel_map, copy=False)
-    return DGLGraph(L, node_frame=G._edge_frame)