annotate ch5ex6-2.py @ 42:039249efe42f
Chapter 6, exercise 2, #4. Wrote a program to output the center column of
a rule 30 CA as a stream of bytes. It is very slow though. It has to run a very
long time to produce enough data for dieharder. Committing it now but will have
to let it run overnight or something to generate a large file.
| author |
Brian Neal <bgneal@gmail.com> |
| date |
Sun, 13 Jan 2013 16:24:00 -0600 |
| parents |
10db8c3a6b83 |
| children |
|
| rev |
line source |
|
bgneal@35
|
1 """Chapter 5.5, exercise 6 in Allen Downey's Think Complexity book.
|
|
bgneal@35
|
2
|
|
bgneal@35
|
3 2. Use the WS model to generate the largest graph you can in a reasonable amount
|
|
bgneal@35
|
4 of time. Plot P(k) versus k and see if you can characterize the tail
|
|
bgneal@35
|
5 behavior.
|
|
bgneal@35
|
6
|
|
bgneal@35
|
7 """
|
|
bgneal@35
|
8 import sys
|
|
bgneal@35
|
9
|
|
bgneal@35
|
10 from matplotlib import pyplot
|
|
bgneal@35
|
11
|
|
bgneal@35
|
12 from Graph import Vertex
|
|
bgneal@35
|
13 from SmallWorldGraph import SmallWorldGraph
|
|
bgneal@35
|
14
|
|
bgneal@35
|
15
|
|
bgneal@35
|
16
|
|
bgneal@35
|
17 def main(script, n, k, p):
|
|
bgneal@35
|
18
|
|
bgneal@35
|
19 # create a SmallWorldGraph with n vertices, k regular edges between
|
|
bgneal@35
|
20 # vertices, and rewiring probability p.
|
|
bgneal@35
|
21
|
|
bgneal@35
|
22 n, k, p = int(n), int(k), float(p)
|
|
bgneal@35
|
23 vs = [Vertex() for i in xrange(n)]
|
|
bgneal@35
|
24
|
|
bgneal@35
|
25 g = SmallWorldGraph(vs, k, p)
|
|
bgneal@35
|
26
|
|
bgneal@35
|
27 # retrieve probabilities
|
|
bgneal@35
|
28 p = g.get_p()
|
|
bgneal@35
|
29
|
|
bgneal@35
|
30 # plot P(k) versus k on a log-log scale
|
|
bgneal@35
|
31
|
|
bgneal@35
|
32 vals = p.items()
|
|
bgneal@35
|
33 vals.sort(key=lambda t: t[0])
|
|
bgneal@35
|
34 x, y = zip(*vals)
|
|
bgneal@35
|
35
|
|
bgneal@35
|
36 assert abs(sum(y) - 1.0) < 1e-6
|
|
bgneal@35
|
37
|
|
bgneal@35
|
38 pyplot.clf()
|
|
bgneal@35
|
39 pyplot.xscale('log')
|
|
bgneal@35
|
40 pyplot.yscale('log')
|
|
bgneal@35
|
41 pyplot.title('P(k) versus k')
|
|
bgneal@35
|
42 pyplot.xlabel('k')
|
|
bgneal@35
|
43 pyplot.ylabel('P(k)')
|
|
bgneal@35
|
44 pyplot.plot(x, y, label='P(k) vs. k', color='green', linewidth=3)
|
|
bgneal@35
|
45 pyplot.legend(loc='upper right')
|
|
bgneal@35
|
46 pyplot.show()
|
|
bgneal@35
|
47
|
|
bgneal@35
|
48
|
|
bgneal@35
|
49 if __name__ == '__main__':
|
|
bgneal@35
|
50 main(*sys.argv)
|
