remove edge list creation (#1688)

tutorials/basics/2_basics.py

@@ -69,10 +69,6 @@ start2 = dgl.DGLGraph((0, v))
 adj = spp.coo_matrix((np.ones(len(u)), (u.numpy(), v.numpy())))
 star3 = dgl.DGLGraph(adj)
 
-# Create the same graph from a list of integer pairs.
-elist = [(0, 1), (0, 2), (0, 3), (0, 4), (0, 5)]
-star4 = dgl.DGLGraph(elist)
-
 ###############################################################################
 # You can also create a graph by progressively adding more nodes and edges.
 # Although it is not as efficient as the above constructors, it is suitable

tutorials/basics/5_hetero.py

@@ -96,14 +96,15 @@ using the heterograph class and its associated API.
 #
 # For instance, the following code creates the user-item interactions heterograph shown earlier.
 
-# Each value of the dictionary is a list of edge tuples.
+# Each value of the dictionary is a pair of source and destination arrays.
 # Nodes are integer IDs starting from zero. Nodes IDs of different types have
 # separate countings.
 import dgl
+import numpy as np
 
 ratings = dgl.heterograph(
-    {('user', '+1', 'movie') : [(0, 0), (0, 1), (1, 0)],
-     ('user', '-1', 'movie') : [(2, 1)]})
+    {('user', '+1', 'movie') : (np.array([0, 0, 1]), np.array([0, 1, 0])),
+     ('user', '-1', 'movie') : (np.array([2]), np.array([1]))})
 
 ###############################################################################
 # DGL supports creating a graph from a variety of data sources. The following
@@ -130,11 +131,6 @@ ratings = dgl.heterograph(
     {('user', '+1', 'movie') : plus1,
      ('user', '-1', 'movie') : minus1})
 
-# Creating from edge indices
-ratings = dgl.heterograph(
-    {('user', '+1', 'movie') : ([0, 0, 1], [0, 1, 0]),
-     ('user', '-1', 'movie') : ([2], [1])})
-
 ###############################################################################
 # Manipulating heterograph
 # ------------------------