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TravSales2opt.py
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TravSales2opt.py
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'''
TravSales2opt Inst
'''
import math
import random
from pylab import *
def hyp(ax, ay, bx, by):
xdiff = ax - bx
ydiff = ay - by
return math.hypot(xdiff, ydiff)
class TravSales2opt(object):
def __init__(self, seed=40):
self.dimension = 500
self.OrderedList = list()
self.num = 100
self.candidateMove = [0, 0]
random.seed(seed)
for i in xrange(0, self.num):
self.OrderedList.append(((random.random() * self.dimension),
(random.random() * self.dimension)))
self.currentCost = self.cost()
self.currentDelta = 0
def genMove(self):
self.candidateMove = [0, 0]
def validMove():
if self.candidateMove[0] == self.candidateMove[1]:
return False
if abs(self.candidateMove[0] - self.candidateMove[1]) < 2:
return False
if self.candidateMove[0] == self.num - 2:
return False
if self.candidateMove[1] == self.num - 2:
return False
return True
while not validMove():
self.candidateMove = [int(random.random() * (self.num - 1)),
int(random.random() * (self.num - 1))]
if self.candidateMove[0] > self.candidateMove[1]:
(self.candidateMove[0], self.candidateMove[1]) = (self.candidateMove[1], self.candidateMove[0])
a = self.candidateMove[0]
b = a + 1
c = self.candidateMove[1]
d = c + 1
delta = (hyp(*(self.OrderedList[a] + self.OrderedList[c]))
+ hyp(*(self.OrderedList[b] + self.OrderedList[d]))
- hyp(*(self.OrderedList[a] + self.OrderedList[b]))
- hyp(*(self.OrderedList[c] + self.OrderedList[d])))
self.currentDelta = delta
return delta
def cost(self):
accumCost = 0.
for i in xrange(0, self.num - 1):
accumCost += hyp(*(self.OrderedList[i] + self.OrderedList[i + 1]))
return accumCost
def commitMove(self):
a = self.candidateMove[0]
b = a + 1
c = self.candidateMove[1]
d = c + 1
newList = self.OrderedList[0:a + 1]
newList += self.OrderedList[c:b - 1:-1]
newList += self.OrderedList[d:]
self.OrderedList = newList
self.candidateMove = [0, 0]
self.currentCost += self.currentDelta
def plotPath(self):
xList = []
yList = []
for (i, v) in self.OrderedList.items():
xList.append(v[0])
yList.append(v[1])
plot(xList, yList, 'go-')
if __name__ == '__main__':
inst = TravSales2opt()
icost = inst.cost()
print "Initial: ", icost
cost = icost
for i in xrange(1, 5):
d = inst.genMove()
print "Delta:", d
inst.commitMove()
inst.plotPath()
show()
cost += d
print "Cost: ", cost
print "Full Cost: ", inst.cost()