“““?Code?example?from?Complexity?and?Computation?a?book?about
exploring?complexity?science?with?Python.??Available?free?from

http://greenteapress.com/complexity

Copyright?2011?Allen?B.?Downey.
Distributed?under?the?GNU?General?Public?License?at?gnu.org/licenses/gpl.html.
“““

import?numpy

class?CA（object）:
????“““A?CA?is?a?cellular?automaton;?the?parameters?for?__init__?are:

????rule:??an?integer?in?the?range?0-255?that?represents?the?CA?rule
???????????using?Wolfram‘s?encoding.
????n:?????the?number?of?rows?（timesteps）?in?the?result.
????ratio:?the?ratio?of?columns?to?rows.
????“““

????def?__init__（self?rule?n=100?ratio=2）:
????????“““Attributes:
????????table:??rule?dictionary?that?maps?from?triple?to?next?state.
????????n?m:???are?the?number?of?rows?columns.
????????array:??the?numpy?array?that?contains?the?data.
????????next:???the?index?of?the?next?empty?row.
????????“““
????????self.table?=?self.make_table（rule）
????????self.n?=?n
????????self.m?=?ratio*n?+?1
????????self.array?=?numpy.zeros（（n?self.m）?dtype=numpy.int8）
????????self.next?=?0

????def?make_table（self?rule）:
????????“““Returns?a?table?for?the?given?CA?rule.??The?table?is?a?
????????dictionary?that?maps?3-tuples?to?binary?values.
????????“““
????????table?=?{}
????????for?i?bit?in?enumerate（binary（rule?8））:
????????????t?=?binary（7-i?3）
????????????table[t]?=?bit
????????return?table

????def?start_single（self）:
????????“““Starts?with?one?cell?in?the?middle?of?the?top?row.“““
????????self.array[0?self.m/2]?=?1
????????self.next?+=?1

????def?start_random（self）:
????????“““Start?with?random?values?in?the?top?row.“““
????????self.array[0]?=?numpy.random.random（[1self.m]）.round（）
????????self.next?+=?1

????def?loop（self?steps=1）:
????????“““Executes?the?given?number?of?time?steps.“““
????????[self.step（）?for?i?in?xrange（steps）]

????def?step（self）:
????????“““Executes?one?time?step?by?computing?the?next?row?of?the?array.“““
????????i?=?self.next
????????self.next?+=?1

????????a?=?self.array
????????t?=?self.table
????????for?j?in?xrange（1self.m-1）:
????????????a[ij]?=?t[tuple（a[i-1?j-1:j+2]）]

????def?get_array（self?start=0?end=None）:
????????“““Gets?a?slice?of?columns?from?the?CA?with?slice?indices
????????（start?end）.??Avoid?copying?if?possible.
????????“““
????????if?start==0?and?end==None:
????????????return?self.array
????????else:
????????????return?self.array[:?start:end]


def?binary（n?digits）:
????“““Returns?a?tuple?of?（digits）?integers?representing?the
????integer?（n）?in?binary.??For?example?binary（33）?returns?（0?1?1）“““
????t?=?[]
????for?i?in?range（digits）:
????????n?r?=?divmod（n?2）
????????t.append（r）

????return?tuple（reversed（t））


def?print_table（table）:
????“““Prints?the?rule?table?in?LaTeX?format.“““
????t?=?table.items（）
????t.sort（reverse=True）

????print?‘\\beforefig‘
????print?‘\\centerline{‘
????print?‘\\begin{tabular}{|c|c|c|c

?屬性????????????大小?????日期????時(shí)間???名稱(chēng)
-----------?---------??----------?-----??----
?????文件????????3344??2016-09-09?20:34??CA.py
?????文件????????5717??2016-09-09?20:44??CAdrawer.py