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# This file is part of DEAP.
#
# DEAP is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 3 of
# the License, or (at your option) any later version.
#
# DEAP is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with DEAP. If not, see <http://www.gnu.org/licenses/>.
try:
from itertools import product
except ImportError:
def product(*args, **kwds):
# product('ABCD', 'xy') --> Ax Ay Bx By Cx Cy Dx Dy
# product(range(2), repeat=3) --> 000 001 010 011 100 101 110 111
pools = map(tuple, args) * kwds.get('repeat', 1)
result = [[]]
for pool in pools:
result = [x+[y] for x in result for y in pool]
for prod in result:
yield tuple(prod)
class SortingNetwork(list):
"""Sorting network class.
From Wikipedia : A sorting network is an abstract mathematical model
of a network of wires and comparator modules that is used to sort a
sequence of numbers. Each comparator connects two wires and sort the
values by outputting the smaller value to one wire, and a larger
value to the other.
"""
def __init__(self, dimension, connectors = []):
self.dimension = dimension
for wire1, wire2 in connectors:
self.addConnector(wire1, wire2)
def addConnector(self, wire1, wire2):
"""Add a connector between wire1 and wire2 in the network."""
if wire1 == wire2:
return
if wire1 > wire2:
wire1, wire2 = wire2, wire1
try:
last_level = self[-1]
except IndexError:
# Empty network, create new level and connector
self.append({wire1: wire2})
return
for wires in last_level.iteritems():
if wires[1] >= wire1 and wires[0] <= wire2:
self.append({wire1: wire2})
return
last_level[wire1] = wire2
def sort(self, values):
"""Sort the values in-place based on the connectors in the network."""
for level in self:
for wire1, wire2 in level.iteritems():
if values[wire1] > values[wire2]:
values[wire1], values[wire2] = values[wire2], values[wire1]
def assess(self, cases=None):
"""Try to sort the **cases** using the network, return the number of
misses. If **cases** is None, test all possible cases according to
the network dimensionality.
"""
if cases is None:
cases = product(range(2), repeat=self.dimension)
misses = 0
ordered = [[0]*(self.dimension-i) + [1]*i for i in range(self.dimension+1)]
for sequence in cases:
sequence = list(sequence)
self.sort(sequence)
misses += (sequence != ordered[sum(sequence)])
return misses
def draw(self):
"""Return an ASCII representation of the network."""
str_wires = [["-"]*7 * self.depth]
str_wires[0][0] = "0"
str_wires[0][1] = " o"
str_spaces = []
for i in xrange(1, self.dimension):
str_wires.append(["-"]*7 * self.depth)
str_spaces.append([" "]*7 * self.depth)
str_wires[i][0] = str(i)
str_wires[i][1] = " o"
for index, level in enumerate(self):
for wire1, wire2 in level.iteritems():
str_wires[wire1][(index+1)*6] = "x"
str_wires[wire2][(index+1)*6] = "x"
for i in xrange(wire1, wire2):
str_spaces[i][(index+1)*6+1] = "|"
for i in xrange(wire1+1, wire2):
str_wires[i][(index+1)*6] = "|"
network_draw = "".join(str_wires[0])
for line, space in zip(str_wires[1:], str_spaces):
network_draw += "\n"
network_draw += "".join(space)
network_draw += "\n"
network_draw += "".join(line)
return network_draw
@property
def depth(self):
"""Return the number of parallel steps that it takes to sort any input.
"""
return len(self)
@property
def length(self):
"""Return the number of comparison-swap used."""
return sum(len(level) for level in self)
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