Shapes
======

Exercise
--------

  * Complete the ```Ellipse(Shape)``` class definition
  * Complete the ```scale(self, factor)``` method within the class definition ```Shape()```
  * Add a method to the each of the classes ```Rectangle(Shape)```, ```Triangle(Shape)```, and ```Ellipse(Shape)``` to calculate the perimeters of the different shapes

.. interactive_code_block:: 
   :caption: Complete the Ellipse(Shape) class definition, the scale() method, and add a method to calculate the perimeters of the three different shapes

   class Shape():
   
       def __init__(self, w, h):  # Special method name __init__: this method gets called when an instance 	of the class is created
           self.width = w  # Instance variable
           self.height = h

       def scale(self, factor):  # Method definition
       	  pass
       	  # ...


   class Rectangle(Shape):  # The class 'Rectangle will 'inherit' everything from the class 'Shape'
   	
       def area(self):
           return self.width * self.height
   
   class Triangle(Shape):  # Isosceles triangle = two sides of equal length [^1] 
   	
       def area(self):
           return self.width * self.height / 2
   		
   class Ellipse(Shape):
   	
       def area(self):
           pass
           # ...
   
   
   # Creating instances of the classes
   r1 = Rectangle(10, 20)
   r2 = Rectangle(20, 30) 
   t = Triangle(20, 30)
   e = Ellipse(40, 50)
   
   
   print('\\n   Shape    | Width  | Height |     Area      ')
   print('------------+--------+--------+---------------')		
   print('Rectangle 1 | {:6.2f} | {:6.2f} | {:13.3f}'.format(r1.width, r1.height, r1.area()))
   print('Rectangle 2 | {:6.2f} | {:6.2f} | {:13.3f}'.format(r2.width, r2.height, r2.area()))
   print('Triangle    | {:6.2f} | {:6.2f} | {:13.3f}'.format(t.width, t.height, t.area()))
   print('Ellipse     | {:6.2f} | {:6.2f} | {:13.3f}'.format(e.width, e.height, e.area()))
   
   r1.scale(1.5) # Call the scale method
   print('Rectangle 1 | {:6.2f} | {:6.2f} | {:13.3f}'.format(r1.width, r1.height, r1.area()))
   
   
   # Output:
   #
   #    Shape    | Width  | Height |     Area      
   # ------------+--------+--------+---------------
   # Rectangle 1 |  10.00 |  20.00 |       200.000
   # Rectangle 2 |  20.00 |  30.00 |       600.000
   # Triangle    |  20.00 |  30.00 |       300.000
   # Ellipse     |  40.00 |  50.00 |      1570.796
   # Rectangle 1 |  15.00 |  30.00 |       450.000
   
   """
   [^1]: https://en.wikipedia.org/wiki/Isosceles_triangle
   """