CSC111 Lab 11 2015

--D. Thiebaut (talk) 19:36, 11 April 2015 (EDT)

---

<onlydft>

The first part of the lab deals with class in general and class inheritance in particular, and you will be building classes derived from other classes.
For the second part, you will be working with text-based information in the form of lists. We often have to deal with lists: they can be list of email addresses, list of contacts, list of courses, list of grad schools, list of historical facts, list of books, or authors, etc. And very often we need to extract just a few items from the list that are of interest to us. Once you know programming, such task can be done very simply. In this lab, you are going to process several lists and extract information from them.
You are encouraged to work in pair programming mode for this lab.
The deadline for the submission on Moodle is Friday 4/17 at 11:00 a.m.

Problem 1: Class Inheritance: Rectangles with Labels Inside

• Create a new program called Lab11_1.py and copy the code below into it.

# lab11_1.py
# ...
# A graphic program with a new MyRect class that is derived from
# the Rectangle class in the graphics.py library.

from graphics import *

# window geometry
WIDTH = 600
HEIGHT = 400


class MyRect( Rectangle ):
    """MyRect: a class that inherits from Rectangle, in graphics.py"""

    def __init__( self, p1, p2, labl ):
        """constructor.  Constructs a rectangle with a text label in its center"""

        # call the Rectangle constructor and pass it the 2 points 
        Rectangle.__init__( self, p1, p2 )

        # put a label at a point in-between p1 and p2.
        midPoint = Point( (p1.getX()+p2.getX())/2,
                          (p1.getY()+p2.getY())/2 )
        self.label = Text( midPoint, labl )

    def draw( self, win ):
        """draw the rectangle and the label on the window."""
        # call the draw() method of the rectangle class to draw the rectangle
        Rectangle.draw( self, win )

        # then draw the label on top
        self.label.draw( win )


def main():
    # open the window
    win = GraphWin( "CSC LAB", WIDTH, HEIGHT )

    # create an object of type MyRect with the string "CSC111" in the middle
    r1 = MyRect( Point( 100, 100 ), Point( 200, 200 ), "CSC111" )
    r1.setFill( "Yellow" )
    r1.draw( win )

    # close the window when the user clicks the mouse 
    win.getMouse()
    win.close()

main()

• Run the program. Verify that it displays a Yellow rectangle with a string in the middle.
• Add a loop to your main program, that will make the rectangle move to the right:

     for i in range( 20 ):
            r1.move( 10,2 )

• Do you observe something strange? What is happening? Think...

• Think some more. Do not move on until you are sure you know what is going on...

• Ok, if you thought that the inherited move() method from the Rectangle class is not what we want to use, because the original Rectangle class does not know anything about the label, you are totally correct. If, furthermore, you thought you needed to create a new move() method for MyRect() that will override the Rectangle move() method, then I'm really impressed!
• Create a new method called move() and base its design on the draw() method, so that it will call Rectangle.move() to make the yellow rectangle move, and it will activate the move() method of the label to make it move by the same dx, dy displacement.
• Verify that your new program makes the rectangle and the label move together (it's ok if you see some jitter in the motion).

Circles with Labels Inside

• Use the same approach to create a new class called MyCirc that is a subclass of Circle, and that displays a circle with a label inside. You can use the same program and add to it.

< br />

• Modify the loop in your main program so that it makes both the MyRect object and the MyCirc object (that you will have created) move together.

Building a Car with MyRect

• Locate the program you wrote a while back, that displays a car on the graphic window (with a body, two wheels and a top).
• In case you had implemented a text label as part of your Car class, please remove it. Make sure your program displays only a car with 2 wheels and two rectangles, one for the body, one for the top.
• Copy the car class in your current program for today's lab.

Using MyRect to build the Body of the Car

• Organize your program so that the MyRect class is listed at the top of the program, along with MyCirc, and then followed by the Wheel and Car classes.
• Modify your Car class so that it uses MyRect instead of Rectangle for its body. Make the label inside the body be a label that is passed in the constructor of the Car.
• Verify that your program correctly displays the modified car.
• Make your car move some deltax, deltay in a loop, the same way you moved the MyRect and MyCirc objects in the previous problem. Verify that the car moves correctly, including its label.

Problem 2: Aquarium

• Point your browser to this page and drag the tank image and a couple fish images to your desktop.

• Write a new program called lab11_2.py and copy/paste the following code in it:

# lab11_2.py
# Displays fish in an aquarium

from graphics import *
import random

WIDTH  = 700   # geometry of the tank2.gif file
HEIGHT = 517

        
def main():
    # open the window
    win = GraphWin( "CSC Aquarium", WIDTH, HEIGHT )

    # display background image
    background = Image( Point( WIDTH//2, HEIGHT//2 ), "tank2.gif" )
    background.draw( win )

    # display the image of a fish at a random location
    fish = Image( Point( random.randrange( WIDTH),
                         random.randrange( HEIGHT) ),
                  "fish0.gif" )
    fish.draw( win )

    # close window when user clicks it
    win.getMouse()
    win.close()
    
main()

• Create a new class called Fish.
• Include a constructor that received the name of the gif file for the fish.
• Include a member variable in the class to hold the image (Image class in graphics.py) of the fish.
• Add a draw() method to the class, that will allow the main program to have the fish draw itself on the graphic window (win).
• Add a moveRandom() method to the class, that will move the image of the fish some random deltaX and deltaY on the graphic window. Reminder: user random.randrange( 10 ) to generate a random number between 0 and 10, and use random.randrange( -10, 0 ) to generate a random number between -10 and 0 (not included).
• Modify the main program so that it simply creates and displays a fish object, as shown below:

def main():
    # open the window
    win = GraphWin( "CSC Aquarium", WIDTH, HEIGHT )

    # display background
    background = Image( Point( WIDTH//2, HEIGHT//2 ), "tank2.gif" )
    background.draw( win )

    # display a fish
    fish = Fish( "fish0.gif" )
    fish.draw( win )

    win.getMouse()
    win.close()

• When your code works, and only then, add a loop to make the fish move:

def main():
    # open the window
    win = GraphWin( "CSC Aquarium", WIDTH, HEIGHT )

    # display background
    background = Image( Point( WIDTH//2, HEIGHT//2 ), "tank2.gif" )
    background.draw( win )
 
    # display a fish
    fish = Fish( "fish0.gif" )
    fish.draw( win )

    # animation loop
    while win.checkMouse() == None:
        fish.moveRandom()

    win.getMouse()
    win.close()

• Modify the moveRandom() method so that the fish disappears from the graphics window, it is moved back on the other side of the aquarium.
• Create a list of 10 fish with the "fish0.gif" image, and add 10 fish with the "fish20.gif" image (or some fish that is headed in the opposite direction).
• Modify the Fish class so that you can define the direction a fish goes into when you create it.
• Verify that the fish swim in the correct direction.
• Demonstrate your program to the lab instructor or a TA when you're done.

List of Lists

Demonstration Example

• Create a new new program called Lab11_demo.py and copy the code from this program.
• Carefully read the program to see what it does, and how it does it.
• Run the program to verify that it works well.
• Edit the text variable, and make it contain only 5 lines of text (it doesn't matter what countries you pick).
• Run your program again and verify that the "top-10" and "last-10" sections still work and do not crash, even though the list contains fewer than 10 tuples.
• Using a similar approach, solve the next two problems.

Problem 3: Animals

The text below contains names of animals and their speed, expressed in miles per hour. Write a Python program called Lab11_3.py (no need to write classes for this problem) based on the preparation problem above, and make your program output the following quantities:

1. The list of all the animals ranked by speed. Fastest first.
2. The 10 fastest animals listed in order of decreasing speed
3. The 10 slowest animals listed in order of increasing speed
4. The ratio of the speeds of the fastest animal versus that of the slowest animal. For example, if the speed of the fastest animal is 50 and the speed of the slowest is 2, then the program should output that the fastest animal is 25 times faster than the slowest one.
5. The list of all the animals (just their name, not their speed) that are faster than a human being ("human" is one of the species listed). Your program should not contain the number 27.9, which is the speed of a human. Instead it should find this number by looking up "human" in one of your lists and get the speed associated for the human.

Black Mamba Snake 20.0 mph 
Cape Hunting Dog 45.0 mph 
Cat (domestic) 30.0 mph 
Cheetah 70.0 mph 
Chicken 9.0 mph 
Coyote 43.0 mph 
Elephant 25.0 mph 
Elk 45.0 mph 
Giant Tortoise 0.2 mph 
Giraffe 32.0 mph 
Gray Fox 42.0 mph 
Greyhound 39.4 mph 
Grizzly Bear 30.0 mph 
Human 27.9 mph 
Hyena 40.0 mph 
Jackal 35.0 mph 
Lion 50.0 mph 
Mongolian Wild Ass 40.0 mph 
Mule Deer 35.0 mph 
Pig (domestic) 11.0 mph 
Pronghorn Antelope 61.0 mph 
Quarter Horse 47.5 mph 
Rabbit (domestic) 35.0 mph 
Reindeer 32.0 mph 
Six-Lined Racerunner 18.0 mph 
Spider (Tegenaria atrica) 1.2 mph 
Squirrel 12.0 mph 
Thomson's Gazelle 50.0 mph 
Three-Toed Sloth 0.1 mph
Warthog 30.0 mph 
Whippet 35.5 mph 
White-Tailed Deer 30.0 mph 
Wild Turkey 15.0 mph 
Wildebeest 50.0 mph 
Zebra 40.0 mph

Problem 4: Presidents

Below is a CSV list (coma-separated values) of past presidents. Using similar Python code as you have used for the previous problem, write a program (Lab11_4.py) that will process this list and output:

1. the list of presidents sorted alphabetically. Your program should simply print the names, one per line. No additional information is required.
2. the list of all the presidents who were associated with the democratic party.
3. the person who was president in 1945.
4. the presidents whose home state was Massachusetts.

Presidency ,President, Took office ,Left office ,Party , Home State
1, George Washington, 30/04/1789, 4/03/1797, Independent, Virginia
2, John Adams, 4/03/1797, 4/03/1801, Federalist, Massachusetts
3, Thomas Jefferson, 4/03/1801, 4/03/1809, Democratic-Republican, Virginia
4, James Madison, 4/03/1809, 4/03/1817, Democratic-Republican, Virginia
5, James Monroe, 4/03/1817, 4/03/1825, Democratic-Republican, Virginia
6, John Quincy Adams, 4/03/1825, 4/03/1829, Democratic-Republican/National Republican, Massachusetts
7, Andrew Jackson, 4/03/1829, 4/03/1837, Democratic, Tennessee
8, Martin Van Buren, 4/03/1837, 4/03/1841, Democratic, New York
9, William Henry Harrison, 4/03/1841, 4/04/1841, Whig, Ohio
10, John Tyler, 4/04/1841, 4/03/1845, Whig, Virginia
11, James K. Polk, 4/03/1845, 4/03/1849, Democratic, Tennessee
12, Zachary Taylor, 4/03/1849, 9/07/1850, Whig, Louisiana
13, Millard Fillmore, 9/07/1850, 4/03/1853, Whig, New York
14, Franklin Pierce, 4/03/1853, 4/03/1857, Democratic, New Hampshire
15, James Buchanan, 4/03/1857, 4/03/1861, Democratic, Pennsylvania
16, Abraham Lincoln, 4/03/1861, 15/04/1865, Republican/National Union, Illinois
17, Andrew Johnson, 15/04/1865, 4/03/1869, Democratic/National Union, Tennessee
18, Ulysses S. Grant, 4/03/1869, 4/03/1877, Republican, Ohio
19, Rutherford B. Hayes, 4/03/1877, 4/03/1881, Republican, Ohio
20, James A. Garfield, 4/03/1881, 19/09/1881, Republican, Ohio
21, Chester A. Arthur, 19/09/1881, 4/03/1885, Republican, New York
22, Grover Cleveland, 4/03/1885, 4/03/1889, Democratic, New York
23, Benjamin Harrison, 4/03/1889, 4/03/1893, Republican, Indiana
24, Grover Cleveland, 4/03/1893, 4/03/1897, Democratic, New York
25, William McKinley, 4/03/1897, 14/9/1901, Republican, Ohio
26, Theodore Roosevelt, 14/9/1901, 4/3/1909, Republican, New York
27, William Howard Taft, 4/3/1909, 4/03/1913, Republican, Ohio
28, Woodrow Wilson, 4/03/1913, 4/03/1921, Democratic, New Jersey
29, Warren G. Harding, 4/03/1921, 2/8/1923, Republican, Ohio
30, Calvin Coolidge, 2/8/1923, 4/03/1929, Republican, Massachusetts
31, Herbert Hoover, 4/03/1929, 4/03/1933, Republican, Iowa
32, Franklin D. Roosevelt, 4/03/1933, 12/4/1945, Democratic, New York
33, Harry S. Truman, 12/4/1945, 20/01/1953, Democratic, Missouri
34, Dwight D. Eisenhower, 20/01/1953, 20/01/1961, Republican, Texas
35, John F. Kennedy, 20/01/1961, 22/11/1963, Democratic, Massachusetts
36, Lyndon B. Johnson, 22/11/1963, 20/1/1969, Democratic, Texas
37, Richard Nixon, 20/1/1969, 9/8/1974, Republican, California
38, Gerald Ford, 9/8/1974, 20/01/1977, Republican, Michigan
39, Jimmy Carter, 20/01/1977, 20/01/1981, Democratic, Georgia
40, Ronald Reagan, 20/01/1981, 20/01/1989, Republican, California
41, George H. W. Bush, 20/01/1989, 20/01/1993, Republican, Texas
42, Bill Clinton, 20/01/1993, 20/01/2001, Democratic, Arkansas
43, George W. Bush, 20/01/2001, 20/01/2009, Republican, Texas

Moodle Submission

Demonstrate the correct behavior of your aquarium to your lab instructor. Submit your solution program for the presidents problem on Moodle, in the Lab11 PB1 section.

<showafterdate after="20150417 11:00" before="20150601 00:00">

Solution Programs

Animals

# animals.py
# D. Thiebaut
# parses a list of lines containing
# animal information and outputs several
# interesting statistics about the quantities
# contained in the text.

text = """Black Mamba Snake 20.0 mph 
Cape Hunting Dog 45.0 mph 
Cat (domestic) 30.0 mph 
Cheetah 70.0 mph 
Chicken 9.0 mph 
Coyote 43.0 mph 
Elephant 25.0 mph 
Elk 45.0 mph 
Giant Tortoise 0.2 mph 
Giraffe 32.0 mph 
Gray Fox 42.0 mph 
Greyhound 39.4 mph 
Grizzly Bear 30.0 mph 
Human 27.9 mph 
Hyena 40.0 mph 
Jackal 35.0 mph 
Lion 50.0 mph 
Mongolian Wild Ass 40.0 mph 
Mule Deer 35.0 mph 
Pig (domestic) 11.0 mph 
Pronghorn Antelope 61.0 mph 
Quarter Horse 47.5 mph 
Rabbit (domestic) 35.0 mph 
Reindeer 32.0 mph 
Six-Lined Racerunner 18.0 mph 
Spider (Tegenaria atrica) 1.2 mph 
Squirrel 12.0 mph 
Thomson's Gazelle 50.0 mph 
Three-Toed Sloth 0.1 mph
Warthog 30.0 mph 
Whippet 35.5 mph 
White-Tailed Deer 30.0 mph 
Wild Turkey 15.0 mph 
Wildebeest 50.0 mph 
Zebra 40.0 mph"""

def main():
    #----------------------------------------------------------
    # display the list sorted by decreasing speed
    #----------------------------------------------------------
    print( "\n\nCOMPLETE LIST, ORDERED BY DECREASING SPEED" )
    list = []
    for line in text.split( "\n" ):
        fields = line.split( )
        # skip lines that do not contain a valid count of fields
        if len( fields ) < 3:
            continue

        # create a name and a speed
        name = fields[0:-2]         # all fields except last 2
        name = " ".join( name )     # join all fields with a space
        speed = float( fields[-2] ) # one before last field

        # create a tuple with speed listed first
        tuple = (speed, name )

        # add it to the list
        list.append( tuple )

    # sort the list in increasing order (smallest speed first)
    list.sort()

    # reverse the list
    list.reverse()

    # display the list
    for speed, name in list:
        print( "{0:30} {1:3.1f}".format( name, speed ) )


    #----------------------------------------------------------
    # display the 10 fastest in order of decreasing speed
    #----------------------------------------------------------
    print( "\n\n10 FASTEST ANIMALS, ORDERED BY DECREASING SPEED" )
    for i in range( min( 10, len( list ) ) ):
        speed, name = list[i]
        print( "{0:30} {1:3.1f}".format( name, speed ) )

    #----------------------------------------------------------
    # display the 10 slowest in order of decreasing speed
    #----------------------------------------------------------
    print( "\n\n10 SLOWEST ANIMALS, ORDERED BY INCREASING SPEED" )
    list.reverse()
    for i in range( min( 10, len( list ) ) ):
        speed, name = list[i]
        print( "{0:30} {1:3.1f}".format( name, speed ) )

    #----------------------------------------------------------
    # display the ratio of fastest to slowest
    #----------------------------------------------------------
    print( "\n\nSPEED-RATIO OF FASTEST TO SLOWEST" )
    fastestSpeed, fastestName = list[-1]
    slowestSpeed, slowestName = list[0]
    print( "The {0:1} is {1:1.0f} times faster than the {2:1}."
           .format( fastestName, fastestSpeed/slowestSpeed, slowestName ))

    #----------------------------------------------------------
    # display the animals faster than human beings
    #----------------------------------------------------------
    print( "\n\nANIMALS FASTER THAN HUMAN BEINGS" )

    # find the speed of the human
    speedHuman = 0
    for speed, name in list:
        if name.strip().lower()=="human":
            speedHuman = speed
            break

    # create a list of the animals faster than humans
    list2 = []
    for speed, name in list:
        if speed > speedHuman:
            list2.append( name )

    # sort the list alphabetically
    list2.sort()

    # display the list
    for name in list2:
        print( "{0:30}".format( name, speed ) )


if __name__=="__main__":
    main()

Presidents

# presidents.py
# D. Thiebaut

text="""Presidency ,President, Took office ,Left office ,Party , Home State
1, George Washington, 30/04/1789, 4/03/1797, Independent, Virginia
2, John Adams, 4/03/1797, 4/03/1801, Federalist, Massachusetts
3, Thomas Jefferson, 4/03/1801, 4/03/1809, Democratic-Republican, Virginia
4, James Madison, 4/03/1809, 4/03/1817, Democratic-Republican, Virginia
5, James Monroe, 4/03/1817, 4/03/1825, Democratic-Republican, Virginia
6, John Quincy Adams, 4/03/1825, 4/03/1829, Democratic-Republican/National Republican, Massachusetts
7, Andrew Jackson, 4/03/1829, 4/03/1837, Democratic, Tennessee
8, Martin Van Buren, 4/03/1837, 4/03/1841, Democratic, New York
9, William Henry Harrison, 4/03/1841, 4/04/1841, Whig, Ohio
10, John Tyler, 4/04/1841, 4/03/1845, Whig, Virginia
11, James K. Polk, 4/03/1845, 4/03/1849, Democratic, Tennessee
12, Zachary Taylor, 4/03/1849, 9/07/1850, Whig, Louisiana
13, Millard Fillmore, 9/07/1850, 4/03/1853, Whig, New York
14, Franklin Pierce, 4/03/1853, 4/03/1857, Democratic, New Hampshire
15, James Buchanan, 4/03/1857, 4/03/1861, Democratic, Pennsylvania
16, Abraham Lincoln, 4/03/1861, 15/04/1865, Republican/National Union, Illinois
17, Andrew Johnson, 15/04/1865, 4/03/1869, Democratic/National Union, Tennessee
18, Ulysses S. Grant, 4/03/1869, 4/03/1877, Republican, Ohio
19, Rutherford B. Hayes, 4/03/1877, 4/03/1881, Republican, Ohio
20, James A. Garfield, 4/03/1881, 19/09/1881, Republican, Ohio
21, Chester A. Arthur, 19/09/1881, 4/03/1885, Republican, New York
22, Grover Cleveland, 4/03/1885, 4/03/1889, Democratic, New York
23, Benjamin Harrison, 4/03/1889, 4/03/1893, Republican, Indiana
24, Grover Cleveland, 4/03/1893, 4/03/1897, Democratic, New York
25, William McKinley, 4/03/1897, 14/9/1901, Republican, Ohio
26, Theodore Roosevelt, 14/9/1901, 4/3/1909, Republican, New York
27, William Howard Taft, 4/3/1909, 4/03/1913, Republican, Ohio
28, Woodrow Wilson, 4/03/1913, 4/03/1921, Democratic, New Jersey
29, Warren G. Harding, 4/03/1921, 2/8/1923, Republican, Ohio
30, Calvin Coolidge, 2/8/1923, 4/03/1929, Republican, Massachusetts
31, Herbert Hoover, 4/03/1929, 4/03/1933, Republican, Iowa
32, Franklin D. Roosevelt, 4/03/1933, 12/4/1945, Democratic, New York
33, Harry S. Truman, 12/4/1945, 20/01/1953, Democratic, Missouri
34, Dwight D. Eisenhower, 20/01/1953, 20/01/1961, Republican, Texas
35, John F. Kennedy, 20/01/1961, 22/11/1963, Democratic, Massachusetts
36, Lyndon B. Johnson, 22/11/1963, 20/1/1969, Democratic, Texas
37, Richard Nixon, 20/1/1969, 9/8/1974, Republican, California
38, Gerald Ford, 9/8/1974, 20/01/1977, Republican, Michigan
39, Jimmy Carter, 20/01/1977, 20/01/1981, Democratic, Georgia
40, Ronald Reagan, 20/01/1981, 20/01/1989, Republican, California
41, George H. W. Bush, 20/01/1989, 20/01/1993, Republican, Texas
42, Bill Clinton, 20/01/1993, 20/01/2001, Democratic, Arkansas
43, George W. Bush, 20/01/2001, 20/01/2009, Republican, Texas"""

def main():
    # remove the first line from the list of lines
    lines = text.split( "\n" )
    lines = lines[1:]

    # create a list of tuples
    list = []
    for line in lines:
        fields = line.split( "," )

        # skip invalid lines
        if len( fields ) != 6:
            continue

        # create tuple
        name = fields[1].strip()
        yearStart = int( fields[2].split( "/" )[2] )
        yearEnd   = int( fields[3].split( "/" )[2] )
        party     = fields[-2].strip()
        state     = fields[-1].strip()
        tuple = ( name, yearStart, yearEnd, party, state )

        # add tuple to list
        list.append( tuple )

    #=========================================================
    # Display the list of presidents in alphabetical order
    #=========================================================
    print( "\n\nAlphabetical List".upper() )
    list.sort()
    for name, y1, y2, party, s in list:
        print( name )
        

    #=========================================================
    # Display the list of presidents associated with the democratic
    # party
    #=========================================================
    print( "\n\nAlphabetical List of Democrats".upper() )
    for name, y1, y2, party, s in list:
        if party.lower().find( "democra" )!= -1:
            print( name )
        
    #=========================================================
    # Display the president in office in 1945
    #=========================================================
    print( "\n\nPresident in office in 1945".upper() )
    for name, y1, y2, party, s in list:
        if y1 <= 1945 <= y2:
            print( name )


    #=========================================================
    # Display the president whose home state was Massachusetts
    #=========================================================
    print( "\n\nPresident from Massachusetts".upper() )
    for name, y1, y2, party, s in list:
        if s.capitalize().find( "Massa" ) != -1:
            print( name )
    
if __name__=="__main__":
    main()

MyRect, MyCirc, Car

# MyRect.py
# D. Thiebaut
# This program illustrates how to create and use derived classes.
# MyRect is derived from Rectangle, in graphics.py
# MyCirc is derived from Cirle, also in graphics.py
# Car uses a MyRect object for its body, and a Rectangle for its top.

from graphics import *

WIDTH = 600
HEIGHT = 400

class MyRect( Rectangle ):
    def __init__( self, p1, p2, labl ):
        Rectangle.__init__( self, p1, p2 )
        midPoint = Point( (p1.getX()+p2.getX())/2,
                          (p1.getY()+p2.getY())/2 )
        self.label = Text( midPoint, labl )

    def draw( self, win ):
        Rectangle.draw( self, win )
        self.label.draw( win )

    def move( self, dx, dy ):
        Rectangle.move( self, dx, dy )
        self.label.move( dx, dy )


class MyCirc( Circle ):
    def __init__( self, centr, rad, labl ):
        Circle.__init__( self, centr, rad )
        self.label = Text( centr, labl )

    def draw( self, win ):
        Circle.draw( self, win )
        self.label.draw( win )

    def move( self, dx, dy ):
        Circle.move( self, dx, dy )
        self.label.move( dx, dy )

class Wheel:
    """a Wheel is 2 concentric circles, the larger one black,
    the smaller one grey."""

    def __init__(self, centr, rad1, rad2 ):
        # make circ1 the smaller of the 2 circles
        self.circ1   = Circle( centr, min( rad1, rad2 ) )
        self.circ2   = Circle( centr, max( rad1, rad2 ) )
        self.circ1.setFill( "grey" )
        self.circ2.setFill( "black" )
        
    def draw( self, win ):
        self.circ2.draw( win )
        self.circ1.draw( win )

    def move( self, dx, dy ):
        self.circ2.move( dx, dy )
        self.circ1.move( dx, dy )
        
class Car:
    def __init__( self, rp, labl ):
        x = rp.getX()
        y = rp.getY()
        p2 = Point( x+180, y+60 )
        self.body = MyRect( rp, p2, labl )
        self.body.setFill( "yellow" )
        self.top  = Rectangle( Point( x+10, y-20 ), Point(x+160, y ) )
        self.top.setFill( "yellow" )
        self.w1   = Wheel( Point( x+20, y+60 ), 20,10 )
        self.w2   = Wheel( Point( x+120, y+60 ), 20,10 )

    def draw( self, win ):
        self.body.draw( win )
        self.w1.draw( win )
        self.w2.draw( win )
        self.top.draw( win )

    def move( self, dx, dy ):
        self.body.move( dx, dy )
        self.top.move( dx, dy )
        self.w1.move( dx, dy )
        self.w2.move( dx, dy )
        
def main():
    # open the window
    win = GraphWin( "CSC111", WIDTH, HEIGHT )

    r1 = MyRect( Point( 100, 100 ), Point( 200, 200 ), "CSC111" )
    r1.setFill( "Yellow" )
    r1.draw( win )

    c1 = MyCirc( Point( 200, 200 ), 20, "BALL" )
    c1.setFill( "red" )
    c1.draw( win )

    car = Car( Point( 100,250 ), "TAXI" )
    car.draw( win )
    
    while win.checkMouse() == None:
        for i in range( 20 ):
            r1.move( 10,2 )
            c1.move( 5, 1 )
            car.move( 1, 0 )
            
        for i in range( 20 ):
            r1.move( -10,-2 )
            c1.move( -5, 1 )

    win.getMouse()
    win.close()

main()

</showafterdate>