We can represent a rectangle by knowing three things: the location of its lower left corner, its width, and its height. Create a class definition for a Rectangle class using this idea. To create a Rectangle object at location (4,5) with width 6 and height 5, we would do the following:
r = Rectangle(Point(4, 5), 6, 5)
Solution.
class Point:
""" Point class for representing and manipulating x,y coordinates. """
def __init__(self, initX, initY):
self.x = initX
self.y = initY
def getX(self):
return self.x
def getY(self):
return self.y
def __str__(self):
return "x=" + str(self.x) + ", y=" + str(self.y)
class Rectangle:
"""Rectangle class using Point, width and height"""
def __init__(self, initP, initW, initH):
self.location = initP
self.width = initW
self.height = initH
loc = Point(4, 5)
r = Rectangle(loc, 6, 5)
print(r)
2.
Add the following accessor methods to the Rectangle class: getWidth, getHeight, __str__.
3.
Add a method area to the Rectangle class that returns the area of any instance:
r = Rectangle(Point(0, 0), 10, 5)
test(r.area(), 50)
Solution.
class Point:
""" Point class for representing and manipulating x,y coordinates. """
def __init__(self, initX, initY):
self.x = initX
self.y = initY
def getX(self):
return self.x
def getY(self):
return self.y
def __str__(self):
return "x=" + str(self.x) + ", y=" + str(self.y)
class Rectangle:
"""Rectangle class using Point, width and height"""
def __init__(self, initP, initW, initH):
self.location = initP
self.width = initW
self.height = initH
def area(self):
return self.width * self.height
4.
Write a perimeter method in the Rectangle class so that we can find the perimeter of any rectangle instance:
r = Rectangle(Point(0, 0), 10, 5)
test(r.perimeter(), 30)
5.
Write a transpose method in the Rectangle class that swaps the width and the height of any rectangle instance:
class Point:
""" Point class for representing and manipulating x,y coordinates. """
def __init__(self, initX, initY):
self.x = initX
self.y = initY
def getX(self):
return self.x
def getY(self):
return self.y
def __str__(self):
return "x=" + str(self.x) + ", y=" + str(self.y)
class Rectangle:
"""Rectangle class using Point, width and height"""
def __init__(self, initP, initW, initH):
self.location = initP
self.width = initW
self.height = initH
def transpose(self):
temp = self.width
self.width = self.height
self.height = temp
6.
Write a new method in the Rectangle class to test if a Point falls within the rectangle. For this exercise, assume that a rectangle at (0,0) with width 10 and height 5 has open upper bounds on the width and height, i.e. it stretches in the x direction from [0 to 10), where 0 is included but 10 is excluded, and from [0 to 5) in the y direction. So it does not contain the point (10, 2). These tests should pass:
Write a new method called diagonal that will return the length of the diagonal that runs from the lower left corner to the opposite corner.
Solution.
class Point:
""" Point class for representing and manipulating x,y coordinates. """
def __init__(self, initX, initY):
self.x = initX
self.y = initY
def getX(self):
return self.x
def getY(self):
return self.y
def __str__(self):
return "x=" + str(self.x) + ", y=" + str(self.y)
class Rectangle:
"""Rectangle class using Point, width and height"""
def __init__(self, initP, initW, initH):
self.location = initP
self.width = initW
self.height = initH
def diagonal(self):
d = (self.width**2 + self.height**2) ** 0.5
return d
8.
In games, we often put a rectangular “bounding box” around our sprites in the game. We can then do collision detection between, say, bombs and spaceships, by comparing whether their rectangles overlap anywhere.
Write a function to determine whether two rectangles collide. Hint: this might be quite a tough exercise! Think carefully about all the cases before you code.
