Homework 4: loops and sequences

Due Saturday, 2012-02-18, 11:59pm

In this homework, you will practice using while loops and working with sequences. You will submit one file, called <lastname>_hw4.py. Remember to include your name and the assignment number in a comment at the top of the file and to use lots of comments in your code, including docstrings for all functions that you define.

The problem

For this assignment, our diskoid lives in a world with pentoids (predators) and plasmoids (food), as well as other diskoids. It has six feelers arranged around its body every 60 degrees, starting from its heading (the "mouth" in the figure). When it activates its feelers, they return a list of 6 integers, each representing what it feels at one position: 1 represents a pentoid, 2 another diskoid, 3 a plasmoid, and 0 nothing. The integers are ordered in a counterclockwise direction, starting with the heading. For example, the list returned by the feelers of the diskoid in the center of the first figure would be [0, 1, 1, 2, 3, 3] and for the diskoid in the center of the second figure would be [0, 0, 3, 0, 3, 3].

In response to what its feelers sense, the diskoid does the following:

If it feels more pentoids than diskoids, it camouflages itself. (This is what would happen in the first figure.)
Otherwise, if it feels any diskoids, it primps (to attract the other diskoid(s)).
Otherwise, it eats up to two of the plasmoids that it feels. It does this by turning in a counterclockwise direction, stopping at each plasmoid and eating it until it's eaten two or runs out of plasmoids. For example, in the second figure above, the diskoid would first turn 120 degrees and eat, then turn 120 degrees and eat again, and then stop.

What you have to do

Define a function count_things, which takes a list that would be returned by the diskoid's sensors and returns a list recording how many pentoids, diskoids, and plasmoids are felt (in that order). For example, for the situations shown in the two figures, the function would do the following:
```
>>> count_things([0, 1, 1, 2, 3, 3])
[2, 1, 2]
>>> count_things([0, 0, 3, 0, 3, 3])
[0, 0, 3]
```
Define a function eat, which takes a list that would be returned by the diskoid's sensors, prints out the turns that the diskoid executes in order to eat the plasmoids, and removes the eaten plasmoids from the list. The function returns nothing. For example, for the situation shown in the second figure, the function would do the following:
```
>>> felt_things = [0, 0, 3, 0, 3, 3]
>>> eat(felt_things)
Turned 120 degrees to eat
Turned 120 degrees to eat
>>> felt_things
[0, 0, 0, 0, 0, 3]
```
Define a function respond, which takes a list that would be returned by the diskoid's sensors, prints out what the diskoid does, and returns the original list, possibly changed (if one or more plasmoids were eaten). The definition of respond should make use of both count_things and eat. Here is what respond would do in the situations in the two figures and a third situation like the first but with only one pentoid:
```
>>> respond([0, 1, 1, 2, 3, 3])
Camouflaged
[0, 1, 1, 2, 3, 3]
>>> respond([0, 0, 3, 0, 3, 3])
Turned 120 degrees to eat
Turned 120 degrees to eat
[0, 0, 0, 0, 0, 3]
>>> respond([0, 1, 0, 2, 3, 3])
Primped
[0, 1, 0, 2, 3, 3]
```

IU | CogSci