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solver.py
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solver.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
import datetime
def trivialSolution(nodeCount):
# build a trivial solution
# every node has its own color
solution = range(0, nodeCount)
# prepare the solution in the specified output format
outputData = str(nodeCount) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def secondTrivial(nodeCount, edges):
#Create tuples of form (node, degree)
degree_tuples = []
for node in range(0,nodeCount):
nodeEdges = [[x,y] for [x,y] in edges if x==node or y==node]
degree = len(nodeEdges)
degree_tuples.append([node, degree])
#Sort by Degree
degree_tuples=sorted(degree_tuples, key=lambda node: node[1], reverse=True)
#Create tuples of form (node, degree, color)
color_tuples = []
i=0
for degree_tuple in degree_tuples:
color_tuples.append([degree_tuple[0],degree_tuple[1],-1])
i=i+1
#use heuristic attempt algorithm to solve
currentColor = 0
#color_tuples[0][2]=0
while len([x for [x,y,z] in color_tuples if z ==-1])>0:
initial_node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if z ==-1][0])
color_tuples[initial_node_index][2]=currentColor
if len([x for [x,y,z] in color_tuples if z ==-1])>0:
for node in color_tuples:
node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if x ==node[0]][0])
if(node[2]==-1):
nodeEdges = [[x,y] for [x,y] in edges if x==node[0] or y==node[0]]
connections = {a for [a,b] in nodeEdges if b==node[0]}|{d for [c,d] in nodeEdges if c==node[0]}
currentColorNodes = {x for [x,y,z] in color_tuples if z==currentColor}
if len(connections¤tColorNodes)== 0:
color_tuples[node_index][2]=currentColor
currentColor += 1
# prepare the solution in the specified output format
numColors = max([z for (x,y,z) in color_tuples])+1
solution = [z for (x,y,z) in sorted(color_tuples, key=lambda node: node[0])]
outputData = str(numColors) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def bruteTrivial(nodeCount, edges, offset):
#Create tuples of form (node, degree)
degree_tuples = []
for node in range(0,nodeCount):
nodeEdges = [[x,y] for [x,y] in edges if x==node or y==node]
degree = len(nodeEdges)
degree_tuples.append([node, degree])
#Sort by Degree
degree_tuples=sorted(degree_tuples, key=lambda node: node[1], reverse=True)
#Create tuples of form (node, degree, color)
color_tuples = []
i=0
for degree_tuple in degree_tuples:
color_tuples.append([degree_tuple[0],degree_tuple[1],-1])
i=i+1
#use heuristic attempt algorithm to solve
currentColor = 0
color_tuples[0+offset][2]=0
while len([x for [x,y,z] in color_tuples if z ==-1])>0:
for node in color_tuples:
node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if x ==node[0]][0])
if(node[2]==-1):
nodeEdges = [[x,y] for [x,y] in edges if x==node[0] or y==node[0]]
connections = {a for [a,b] in nodeEdges if b==node[0]}|{d for [c,d] in nodeEdges if c==node[0]}
currentColorNodes = {x for [x,y,z] in color_tuples if z==currentColor}
if len(connections¤tColorNodes)== 0:
color_tuples[node_index][2]=currentColor
currentColor += 1
if len([x for [x,y,z] in color_tuples if z ==-1])>0:
initial_node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if z ==-1][0])
color_tuples[initial_node_index][2]=currentColor
return color_tuples
def brute(nodeCount, edges):
all_tuples = []
for i in range(0,nodeCount):
all_tuples.append(bruteTrivial(nodeCount,edges,i))
min_colors = min(max([z for (x,y,z) in tup]) for tup in all_tuples )
color_tuples = [a for a in all_tuples if max([z for (x,y,z) in a])==min_colors][0]
# prepare the solution in the specified output format
numColors = max([z for (x,y,z) in color_tuples])+1
solution = [z for (x,y,z) in sorted(color_tuples, key=lambda node: node[0])]
outputData = str(numColors) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def getUpperBound(nodeCount, edges):
#Create tuples of form (node, degree)
degree_tuples = []
for node in range(0,nodeCount):
nodeEdges = [[x,y] for [x,y] in edges if x==node or y==node]
degree = len(nodeEdges)
degree_tuples.append([node, degree])
#Sort by Degree
degree_tuples=sorted(degree_tuples, key=lambda node: node[1], reverse=True)
#Create tuples of form (node, degree, color)
color_tuples = []
i=0
for degree_tuple in degree_tuples:
color_tuples.append([degree_tuple[0],degree_tuple[1],-1])
i=i+1
#use heuristic attempt algorithm to solve
currentColor = 0
#color_tuples[0][2]=0
while len([x for [x,y,z] in color_tuples if z ==-1])>0:
initial_node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if z ==-1][0])
color_tuples[initial_node_index][2]=currentColor
if len([x for [x,y,z] in color_tuples if z ==-1])>0:
for node in color_tuples:
node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if x ==node[0]][0])
if(node[2]==-1):
nodeEdges = [[x,y] for [x,y] in edges if x==node[0] or y==node[0]]
connections = {a for [a,b] in nodeEdges if b==node[0]}|{d for [c,d] in nodeEdges if c==node[0]}
currentColorNodes = {x for [x,y,z] in color_tuples if z==currentColor}
if len(connections¤tColorNodes)== 0:
color_tuples[node_index][2]=currentColor
currentColor += 1
# prepare the solution in the specified output format
return max([z for (x,y,z) in color_tuples])+1
def firstAttempt(nodeCount, edges):
# build a trivial solution
# every node has its own color
solution = range(0, nodeCount)
solution[0] = 0
for node in range(1,nodeCount):
nodeColor = range(0,nodeCount)
for edgePair in range(0,nodeCount):
#Check if edge exists
edge1 = (node,edgePair)
edge2 = (edgePair,node)
if edge1 in edges:
nodeColor = filter(lambda a: a!= solution[edgePair], nodeColor)
if edge2 in edges:
nodeColor = filter(lambda a: a!= solution[edgePair], nodeColor)
solution[node] = min(nodeColor)
# prepare the solution in the specified output format
outputData = str(max(solution)+1) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def secondAttempt(nodeCount, edges):
#Create tuples of form (node, degree)
degree_tuples = []
for node in range(0,nodeCount):
nodeEdges = [[x,y] for [x,y] in edges if x==node or y==node]
degree = len(nodeEdges)
degree_tuples.append([node, degree])
#Sort by Degree
degree_tuples=sorted(degree_tuples, key=lambda node: node[1], reverse=True)
#Create tuples of form (node, degree, color)
color_tuples = []
i=0
for degree_tuple in degree_tuples:
color_tuples.append([degree_tuple[0],degree_tuple[1],-1])
i=i+1
#use 1st attempt algorithm to solve
for colorTuple in color_tuples:
nodeColor = range(0,nodeCount)
for edgePair in range(0,nodeCount):
#Check if edge exists
edge1 = (colorTuple[0],edgePair)
edge2 = (edgePair,colorTuple[0])
vertexColor = [z for (x,y,z) in color_tuples if x==edgePair ][0]
if edge1 in edges:
nodeColor = filter(lambda a: a!= vertexColor, nodeColor)
if edge2 in edges:
nodeColor = filter(lambda a: a!= vertexColor, nodeColor)
colorTuple[2] = min(nodeColor)
# prepare the solution in the specified output format
numColors = max([z for (x,y,z) in color_tuples])+1
solution = [z for (x,y,z) in sorted(color_tuples, key=lambda node: node[0])]
outputData = str(numColors) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def thirdAttempt(nodeCount, edges, offset):
#Create tuples of form (node, degree)
color_tuples = []
neighbors = []
for node in range(0,nodeCount):
emptySet = set()
neighbors.append(emptySet)
for edge in edges:
neighbors[edge[0]].add(edge[1])
neighbors[edge[1]].add(edge[0])
for node in range(0,nodeCount):
color_tuples.append([node, len(neighbors[node]), -1])
#Sort by Degree
color_tuples=sorted(color_tuples, key=lambda node: node[1], reverse=True)
#use heuristic attempt algorithm to solve
currentColor = 0
#color_tuples[0][2]=0
hasRun = False
while len([x for [x,y,z] in color_tuples if z ==-1])>0:
startNode = 0
startNode = 0 if hasRun else offset
initial_node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if z ==-1][startNode])
color_tuples[initial_node_index][2]=currentColor
initialNode = color_tuples[initial_node_index][0]
hasRun=True
if len([x for [x,y,z] in color_tuples if z ==-1])>0:
#find list of non-neighbors to initial node
NonNeighbors = range(0,nodeCount)
for node in [[x,y,z] for [x,y,z] in color_tuples if z !=-1]:
NonNeighbors.remove(node[0])
ColorNeighbors=set()
#NonNeighbors.remove(initialNode)
for i in neighbors[initialNode]:
if i in NonNeighbors: NonNeighbors.remove(i)
ColorNeighbors.add(i)
while len(NonNeighbors)>0:
#find the non-neighbor with the most neighbors in common with initial node
biggestNN=-1
biggestSize=-1
for NN in NonNeighbors:
if len(ColorNeighbors & neighbors[NN]) > biggestSize:
biggestNN=NN
biggestSize = len(ColorNeighbors & neighbors[NN])
#color this node same as initial node
node_index = color_tuples.index([[x,y,z] for [x,y,z] in color_tuples if x ==biggestNN][0])
color_tuples[node_index][2] = currentColor
NonNeighbors.remove(biggestNN)
for i in neighbors[biggestNN]:
if i in NonNeighbors: NonNeighbors.remove(i)
ColorNeighbors.add(i)
currentColor += 1
# prepare the solution in the specified output format
numColors = max([z for (x,y,z) in color_tuples])+1
solution = [z for (x,y,z) in sorted(color_tuples, key=lambda node: node[0])]
outputData = str(numColors) + ' ' + str(0) + '\n'
outputData += ' '.join(map(str, solution))
return outputData
def thirdRecursive(nodeCount, edges):
bestSize = nodeCount
bestOut = ''
for i in range(0,10):
tempOut = thirdAttempt(nodeCount, edges, i)
outLines=tempOut.splitlines()
size = int(outLines[0].split()[0])
if size<bestSize:
bestSize=size
bestOut=tempOut
return bestOut
def solverAttempt (nodeCount, edges):
#Create solver model file
upperBound=getUpperBound(nodeCount,edges)
path='C:\\Solver\\bin\\'
filename='test_'+str(nodeCount)+'_'+str(datetime.datetime.now().date())+'_'+ str(datetime.datetime.now().hour)+'_'+str(datetime.datetime.now().minute)+'_'+str(datetime.datetime.now().second)+'.mzn'
solverFile = open(path+filename,'w')
solverFile.write('%G12 Solver File for '+str(nodeCount)+' nodes run at '+ str(datetime.datetime.now())+'\n')
solverFile.write('int: nc='+str(nodeCount)+'; \n')
solverFile.write('\n')
solverFile.write('array[0..nc] of var 0..'+str(upperBound)+': color; \n')
solverFile.write('\n')
solverFile.write('constraint color[0]=0;')
solverFile.write('\n')
for edge in edges:
solverFile.write('constraint color['+str(edge[0])+']!=color['+str(edge[1])+']; \n')
solverFile.write('\n')
solverFile.write('solve minimize max(color); \n')
solverFile.write('')
solverFile.write('output [ show(color[i]) ++"\\n" | i in 0..nc]; \n')
solverFile.close()
#run solver and get solution
import os
from subprocess import check_output as qx
os.chdir('c:\\Solver\\bin')
cmd = r'mzn-g12fd.bat '+filename
output = qx(cmd)
os.chdir('C:\\Users\\keseaman\\Dropbox\\Coursera\\Discrete Optimization\\coloring')
lines=output.splitlines();
#format output and return
numColors = int(max(lines [:nodeCount]))+1
opt = 0
if lines [-1]=='==========': opt = 1
outputData = str(numColors) + ' ' + str(opt) + '\n'
outputData += ' '.join(map(str, lines[:nodeCount]))
return outputData;
def solverAttempt2 (nodeCount, edges):
try:
#Create a new Model
m = Model("myModel")
except GurobiError:
print 'Error Reported'
return 'Test'
def solveIt(inputData):
# Modify this code to run your optimization algorithm
# parse the input
lines = inputData.split('\n')
firstLine = lines[0].split()
nodeCount = int(firstLine[0])
edgeCount = int(firstLine[1])
#
#
#
edges = []
for i in range(1, edgeCount + 1):
line = lines[i]
parts = line.split()
edges.append((int(parts[0]), int(parts[1])))
#outputData = trivialSolution(nodeCount)
#outputData = firstAttempt(nodeCount, edges)
#outputData = secondAttempt(nodeCount, edges)
#outputData = secondTrivial(nodeCount, edges)
#outputData = brute(nodeCount, edges)
#outputData = solverAttempt(nodeCount, edges)
#outputData = solverAttempt2(nodeCount, edges)
#outputData = thirdAttempt(nodeCount, edges, 0)
outputData = thirdRecursive(nodeCount, edges)
return outputData
import sys
if __name__ == '__main__':
if len(sys.argv) > 1:
fileLocation = sys.argv[1].strip()
inputDataFile = open(fileLocation, 'r')
inputData = ''.join(inputDataFile.readlines())
inputDataFile.close()
print solveIt(inputData)
else:
print 'This test requires an input file. Please select one from the data directory. (i.e. python solver.py ./data/gc_4_1)'