Root nodes have no neighbors on directed graphs

[eliorc]

Nodes with no in-degrees generate walks with only themselves - meaning they cannot be considered while traveling and this effects directed graphs.

To reproduce:

import networkx as nx
from node2vec import Node2Vec

DG = nx.DiGraph()
DG.add_edges_from([('1', '2'), ('2', '5'), ('2', '6'), ('3', '4'),
                   ('4', '5'), ('4', '6'), ('5', '7'), ('5', '8'),
                   ('6', '7'), ('6', '8'), ('7', '9'), ('8', '10')])

node2vec = Node2Vec(DG, dimensions=10, walk_length=10, num_walks=400, workers=1)
model = node2vec.fit(window=10)


for walk in node2vec.walks:
    if '1' in walk:
        print(walk)

Results in output of

['1']
['1']
['1']
['1']
.
.
.
.

[eliorc]

Fixed in version v0.3.3