English: The evolution of a network by the Barabasi–Albert model. In every step, one new node appears, and in this case there is two new edges from the new node to the old ones.
Magyar: Egy hálózat fejlődése a Barabási–Albert modell szerint. Minden lépésben egy új csúcs jelenik meg, és ebben a változatban minden új csúcsból két él mutat a régi csúcsokhoz.
The code is (using the python-networkx and python-matplotlib packages on Ubuntu GNU/Linux distribution):
#! /usr/bin/python # coding: utf-8 import networkx #import pylab from pylab import pi, cos, sin, linspace, array import matplotlib.pyplot as plt import os node_number = 20 initial_nodes = 2 animation = False animation = True G=networkx.barabasi_albert_graph(node_number, initial_nodes) # pos=networkx.graphviz_layout(G, prog="dot") type="shell4" pos=networkx.shell_layout(G) #pos=networkx.graphviz_layout(G,prog='twopi',args=) print pos dir=os.path.join("images", type) if not os.path.isdir(dir): os.mkdir(dir) Ge = networkx.empty_graph(node_number) #networkx.draw(GG,pos, node_color="w") for i in range(initial_nodes,node_number): nodes = range(i+1) GG = G.subgraph(nodes) plt.figure(figsize=(8,8)) networkx.draw(GG,pos, node_color="w", alpha=0.5, node_color="blue", node_size=20, with_labels=False, hold=False) #networkx.draw(Ge,pos, node_color="w", alpha=0.5, node_color="blue", node_size=20, with_labels=False, hold=True) #nx.draw(G,pos,node_size=20,alpha=0.5,node_color="blue", with_labels=False) xmax=max(xx for xx,yy in pos.values()) xmin=min(xx for xx,yy in pos.values() + [(0,0)]) ymax=max(yy for xx,yy in pos.values()) ymin=min(yy for xx,yy in pos.values() + [(0,0)]) dx = xmax - xmin ddx=0.1*dx dy = ymax - ymin ddy=0.1*dy plt.xlim(xmin-ddx,xmax+ddx) plt.ylim(ymin-ddy,ymax+ddy) plt.savefig("%s/barabasi_%s%02d.png" % (dir, type, i)) if animation: input = os.path.join(dir, "*.png") output = os.path.join(dir, "barabasi_albert.gif") os.system("convert -delay 100 -loop 0 %s %s" % (input, output))
(If someone knows how to eliminate the frame around the network, write to me, please.)
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{{Information |Description={{en|1=The evolution of a graph by the Barabasi Albert model. In every step, one new node appears, and in this case there is two new edges from the new node to the old ones. }} {{hu|1=Egy gráf fejlődése a Barabási-Albert mod
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