def select_random_nodes(digraph, m, indeg=None, sum=-1):
'''
Randomly select nodes based on probability as per DPA
:param V: input indeg dictionaries
:return: a list of selected nodes V1
'''
if indeg == None:
indeg = graph_util.compute_in_degrees(digraph)
sum = totalindeg(indeg)
prob = [(indeg[j] + 1.0) / (sum + len(digraph)) for j in digraph.keys()]
# print digraph.keys()
# print prob
V1 = nm.random.choice(digraph.keys(), m, True, prob)
return V1
def DPA(n, m):
'''
DPA Algorithm to generate random directed graphs
:param n: number of nodes
:param m: integer (1 <= m <= n)
:return:A directed graph
'''
gE = graph_util.make_complete_graph(m)
indeg = graph_util.compute_in_degrees(gE)
totindeg = totalindeg(indeg)
for i in range(m, n):
V1 = select_random_nodes(gE, m, indeg, totindeg)
gE[i] = set(V1)
for j in V1:
indeg[j] = indeg[j] + 1
indeg[i] = 0
totindeg = totindeg + len(V1)
return gE
