def reward(g: nx.MultiGraph, edge: Tuple[int, int], const_amt: int, fee_type: str, fee: int = None) -> int:
# debugging
# print_flag = fee is not None
u, v = edge
if fee is not None:
g.update_fee(u, v, fee, fee_type)
else:
fee = getattr(g.get_policy(u, v), fee_type)
ebc = edge_betweenness(g, const_amt)[edge]
# debugging
# if print_flag:
# print('({:>3d}, {:>3d}) fee {:>9d} ebc {:>9f} '.format(
# u, v, fee, ebc), end='')
return fee * ebc
def build_node(g: nx.MultiGraph, new_node: int, n: int, const_amt: int, fee_type: str) -> List:
selected = []
# 2 initial edges so routes can pass through new node
while len(selected) < n:
max_reward = 0
best_channel = None
# try all channels
for node in g.nodes():
if node == new_node or node in g[new_node]:
continue
# create new channel
g.add_edge_with_init(new_node, node, default=True)
# calculate max reward
reward, fee = maximise_fee(
g, (new_node, node), const_amt, fee_type)
# select channel if highest reward
if max_reward <= reward:
max_reward = reward
best_channel = (node, fee)
# reset graph for next channel
g.remove_edge(new_node, node)
if best_channel is None:
raise Exception('Profit not possible.')
# add selected channel and redo for next channel
selected.append((new_node, best_channel[0], best_channel[1]))
g.add_edge_with_init(new_node, best_channel[0], default=True)
g.update_fee(new_node, best_channel[0], best_channel[1], fee_type)
# return node with selected channels
return selected
