Python makerandomtree Examples

Example #1

File: geneticProgramming.py Project: mandlamoyo/useful-python-functions

def evolve(pc,popsize,rankfunction,maxgen=500,mutationrate=0.1,breedingrate=0.4,pexp=0.7,pnew=0.05,previouswinner=0):
	def selectindex():
		return int(log(random())/log(pexp))
	
	population=[makerandomtree(pc) for i in range(popsize)]
	if previouswinner!=0:
			population.pop()
			population.append(previouswinner)
			
	for i in range(maxgen):
		scores=rankfunction(population)
		print scores[0][0]
		if scores[0][0]==0: break
		
		newpop=[scores[0][1],scores[1][1]]
		
		while len(newpop)<popsize:
			if random()>pnew:
				newpop.append(mutate(crossover(scores[selectindex()][1],scores[selectindex()][1],probswap=breedingrate),pc,probchange=mutationrate))
			else:
				newpop.append(makerandomtree(pc))
				
		population=newpop
	scores[0][1].display()
	return scores[0][1]

Example #2

File: geneticProgramming.py Project: mandlamoyo/useful-python-functions

def mutate(t,pc,probchange=0.1):
	if random()<probchange:
		return makerandomtree(pc)
	else:
		result=deepcopy(t)
		if isinstance(t,node):
			result.children=[mutate(c,pc,probchange) for c in t.children]
		return result