ant.py

#!/usr/bin/python

import numpy as np
import random

# first condition: average: 4.5
def crossed1(p1, p2):
	x1, y1 = p1
	x2, y2 = p2
	# p1 should be within; 
	# p2 should be on the border or out on the other side
	cond1 = -20 < x1 and x1 < 20 and -20 < y1 and y1 < 20
	cond2 = x2 <= -20 or x2 >= 20 or y2 <= -20 or y2 >= 20
	return cond1 and cond2


# second condition 
def crossed2(p1, p2):
	def f(x) : return 10 - x
	x1, y1 = p1
	x2, y2 = p2
	cond1 = y1 < f(x1)
	cond2 = y2 >= f(x2)
	return cond1 and cond2 


# third condition; average: 14
def crossed3(p1, p2):
	def within(x, y) : 
		return ((x - 2.5) / 30) ** 2 + ((y - 2.5) / 40) ** 2 < 1 
	x1, y1 = p1
	x2, y2 = p2
	cond1 = within(x1, y1)
	cond2 = not within(x2, y2) 
	return cond1 and cond2


def movep(p):
	directions = [(0, 10), (0, -10), (10,0), (-10, 0)]
	(dx, dy) = random.choice(directions)
	return (p[0] + dx, p[1] + dy)
	

def round():
	oldp = (0, 0)
	t = 0
	while True:
		newp = movep(oldp)
		t += 1
		if crossed(oldp, newp): break
		oldp = newp
	return t


def sim(n):
	ts = [0] * n
	for i in range(n):
		ts[i] = round()
		print("Round #", i, ts[i])
	print(np.mean(ts), np.median(ts))
  
  
sim(10000)