Beta-diversity of networks, using python and networkx

pybl.py

import networkx as nx

def B01(a,b,c):
  return (a+b+c)/(float((2*a+b+c)*0.5))-1

def BetaLink(w1,w2,Bf=B01):
	SharedS = list(set(w1.node) & set(w2.node))
	SharedE = list(set(w1.edges()) & set(w2.edges()))
	## Species
	Sc = len(w1.node)-len(SharedS)
	Sb = len(w2.node)-len(SharedS)
	Sa = len(SharedS)
	BS = Bf(Sa,Sb,Sc)
	## All links
	Wc = len(w1.edges()) - len(SharedE)
	Wb = len(w2.edges()) - len(SharedE)
	Wa = len(SharedE)
	WN = Bf(Wa,Wb,Wc)
	## Links between shared species
	nw1 = nx.DiGraph(w1)
	nw2 = nx.DiGraph(w2)
	uSp1 = [n for n in nw1 if n not in SharedS]
	uSp2 = [n for n in nw2 if n not in SharedS]
	nw1.remove_nodes_from(uSp1)
	nw2.remove_nodes_from(uSp2)
	SharedO = list(set(nw1.edges()) & set(nw2.edges()))
	Oc = len(nw1.edges()) - len(SharedO)
	Ob = len(nw2.edges()) - len(SharedO)
	Oa = len(SharedO)
	OL = Bf(Oa,Ob,Oc)
	## Return results
	return [BS,WN,OL,WN-OL,OL/float(WN)*100,(WN-OL)/float(WN)*100]