import networkx as nx
import matplotlib.pyplot as plt

def savegraph(G,i):
	
	G=nx.random_geometric_graph(200,0.125)
	# position is stored as node attribute data for random_geometric_graph
	#pos=nx.get_node_attributes(G,'pos')

	# find node near center (0.5,0.5)
	#dmin=1
	#ncenter=0
	#for n in pos:
	#    x,y=pos[n]
	#    d=(x-0.5)**2+(y-0.5)**2
	#    if d<dmin:
	#        ncenter=n
	#        dmin=d

	ncenter = .5
	dmin = .5

	# color by path length from node near center
	p=nx.single_source_shortest_path_length(G,ncenter)

	plt.figure(figsize=(8,8))
	nx.draw_networkx_edges(G,pos,nodelist=[ncenter],alpha=0.4)
	nx.draw_networkx_nodes(G,pos,nodelist=p.keys(),
	                       node_size=80,
	                       node_color=p.values(),
	                       cmap=plt.cm.Reds_r)

	plt.xlim(-0.05,1.05)
	plt.ylim(-0.05,1.05)
	plt.axis('off')
	name = "graph " + str(i) + ".png"
	plt.savefig(name)