Lecture Notes on 11 August 2014

import math

class Point (object):
  # constructor
  def __init__ (self, x = 0, y = 0):
    self.x = x
    self.y = y

  # get distance to another Point
  def dist (self, other):
    return math.hypot (self.x - other.x, self.y - other.y)

  # string representation of a Point
  def __str__ (self):
    return '(' + str(self.x) + ', ' + str(self.y) + ')'

  # test if two Points are the same
  def __eq__ (self, other):
    tol = 1.0e-16
    return (abs(self.x - other.x) < tol) and (abs(self.y - other.y) < tol)

class Circle (object):
  # constructor
  def __init__ (self, radius = 0, x = 0, y = 0):
    self.radius = radius
    self.center = Point (x, y)

  # compute circumference
  def circumference (self):
    return 2.0 * math.pi * self.radius

  # compute area
  def area (self):
    return math.pi * self.radius * self.radius

  # determine if a Point is inside a circle
  def point_within (self, p):
    distance = self.center.dist (p)
    return (distance < self.radius)

  # determine if a circle other is completely within
  def circle_within (self, other):
    distance = self.center.dist (other.center)
    return (distance + other.radius) < self.radius

  # string representation of a circle
  def __str__ (self):
    return 'Radius: ' + str(self.radius) + ' Center: ' + str (self.center)

  # test for equality
  def __eq__ (self, other):
    tol = 1.0e-16
    return (abs(self.radius - other.radius) < tol)

def main():
  # create Point objects
  p = Point()
  q = Point (3, 5)

  # print the Point objects
  print (p)
  print (q)

  # change the coordinates of a Point object
  p.x += 1
  p.y += 2
  print (p)

  # get distance between two Point objects
  print (p.dist(q))
  print (q.dist(p))

  # test for equality of two Point objects
  if (p == q):
    print (str(p) + ' and ' + str(q) + ' are equal')
  else:
    print (str(p) + ' and ' + str(q) + ' are not equal')

  # create Circle objects
  circleA = Circle (3.0, 0, 5)
  print (circleA)

  circleB = Circle (1618, 8, 6)
  print (circleB.area())

  if (circleB.circle_within(circleA)):
    print (str(circleA) + " is within " + str(circleB))
  else:
    print (str(circleA) + " is not within " + str(circleB))

main()