Introductory Programming
Fall 2004

Homework 10

The reading for this assignment is Chapter 12 of How to think....

Back to AmoebaWorld!

  1. wget http://wb/ip/code/ and make a copy named You should have a hardcopy of; read it and make sure you understand it.

  2. Run and confirm that it does what you expect.

  3. Modify the program so that it creates a third Amoeba named pat. If you type more /usr/X11R6/lib/X11/rgb.txt you will see a list of the color names Python recognizes. You can make pat any color you want. Inside the loop, add a line to move pat and remove the lines that invoke nudge. Run the program again.

  4. Rather than invoke move three times, you can use a for loop to move each of the Amoebas. The object named world has an attribute named animals that is a list of the animals that have been instantiated.

    First, add a line of code (after you create the third Amoeba) and print world.animals. Run the program and confirm that the list contains three instances.

    Now replace the three move calls with a loop that traverses the list of animals and calls move for each one. Run the program and confirm that the Amoebas still move.

  5. The next step is to detect and handle collisions between Amoebas:

    Create a new function called collide that takes two Amoebas as parameters. For now, it should just print the two Amoebas.

    Now write a function called check_collisions that takes an Amoeba and a list of Amoebas. For each Amoeba in the list, it should compute the distance to the given Amoeba. If the distance is less than 1, it should invoke collide.

    Finally add code in main to detect collisions by invoking check_collisions.

  6. Since you took out the nudge statements, you might find that it takes a while for Amoebas to find each other. But now that there are more than two Amoebas, it's not as clear who should be chasing who.

    Add an attribute named crush to each Amoeba. For each Amoeba crush should be another Amoeba. If you are feeling mischievous, you can create a love triangle. Now modify move so that after invoking teleport, it invokes nudge to move the Amoeba closer to crush.

  7. Inside mate, you can print the Amoeba objects, but you might notice that Amoebas don't really know their names! Add an attribute named name to each Amoeba. Modify collide so it prints the names of the Amoebas that collided.

  8. Modify make_amoeba so that each Amoeba has an attribute named spouse that is initially None.

    Modify mate so that if two Amoebas collide, and neither one has a spouse, they get married (using your code from Evaluation 7). You might want to change the color of the nucleus (the color2 attribute) to indicate which Amoebas are married.

  9. Challenge: Modify mate so that if two Amoebas collide, and they are already married, they create a new smaller Amoeba. The new Amoeba should have an attribute that identifies it as a juvenile, so that if it collides with another Amoeba, it doesn't get married.

  10. Challenge: Make Amoebas wait at least 20 moves after they get married and before they spawn another Amoeba.