A Very Fishy Problem

Previously in lecture, we discussed Python classes, which allow us to define our own data types that combine data (instance variables) and operations (instance methods). In this lab, we will use classes to create a virtual aquarium.

1. StartbycompletingtheFishclass,whichwillrepresentasinglefishinouraquarium.EveryFishhasfourattributes, represented as instance variables: its name, its species, its color, and its weight in ounces. A Fish also has the following methods (with the following headers):

__init__(self, name, species, color, weight)

This method creates four new instance variables for the current Fish, and assigns them the values of the last four method parameters. Remember that an instance variables name is always preceded by "self.", as inself.myData.

__repr__(self) This method returns a string representing the current Fish. This string should include a crude fish symbol (<><)

followed by the Fishs name, color, and species in parentheses. For example:

 <>< (Topper, blue Guppy) 

__lt__(self, other)

This method returns True if the current Fishs weight is less than the other Fishs weight instance variable, and False otherwise. Remember that Python does not protect instance variables from outside access, so you can directly refer to the weight instance variable from the other parameter.

kind(self) This method returns the species of the current Fish.

2. Complete the createFish() function, which takes a single string argument in the form:

species name color weight

where each field is separated by a single space (assume that the species and name are always single-word values). This function should create and return a new Fish object whose attributes are based on the contents of this string. Note that the fields of the string are in a slightly different order than the argument list of the Fish class, and that the weight value must be converted from a string to a float value before the new Fish is created.

3. We also need an aquarium to hold our fish. To do this, we need to define a second class, named Aquarium. AnAquarium has two instance variables: a list of Fish instances, and an integer representing the water capacity of the tank in gallons (each Fish requires 1 gallon of water). An Aquarium also has the following methods:

__init__(self, capacity)

This method creates a new instance variable that is an empty list; this list will eventually be filled with Fishobjects. It also assigns its second parameter to a new instance variable representing the Aquariums total capacity in gallons.

__repr__(self)

This method returns a single string that contains the string representations of the Fish in the Aquariums internal list, in the same order that they appear in that list. Insert tab ("\t") and newline (" ") characters to ensure that, when this string is displayed, no more than two Fish are printed per line (if there are an odd number of fish, the last one will be printed on a line by itself). For example, a call to this method might return a string like

"<>< (Bill, red Gourami)\t<>< (Ted, yellow Goldfish) <>< (Mary, pink Mollie)". Note that you can call str() on a Fish (or any other object) to automatically invoke its __repr__() method.

CSE 101 Fall 2018 Lab #8 Page 2

add(self, newFish) If the number of Fish in the Aquarium is less than its capacity, this method appends its argument to the list of

Fish and returns True. Otherwise, it returns False without modifying the list.

population(self)

This method returns the number of Fish that are currently held in the Aquarium.

countType(self, type)

This method returns the number of Fish in the Aquarium whose species matches the type parameter. For example, myTank.countType("Guppy") would return the number of Fish in myTank that have Guppy as their species.

4. Finally, complete the fillAquarium() function. This function takes two arguments: a string representing the name of a (plain text) data file, and a positive (non-zero) integer representing the tank capacity in gallons. It returns a new Aquarium object. fillAquarium() does the following:

(a) It creates a new Aquarium with the specified capacity. (b) It uses a loop to open the specified data file. For each line in the data file:

The function calls createFish() with the current line to get a new Fish.

The function attempts to add the new Fish to the Aquarium object. (c) It returns the new Aquarium.

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Sample Output

When you have completed the assignment, your program should produce output similar to the following using the supplied sample data files:

Creating three new fish... Fish 1: <>< (Homer, red Guppy) Fish 1 is a Guppy Fish 2: <>< (Marge, blue Cichlid) Fish 2 is a Cichlid Fish 3: <>< (Bart, yellow Tetra) Fish 3 is a Tetra Fish 1 is larger than Fish 2 Fish 1 is larger than Fish 3 The test tanks current population is: 0 Adding fish now... The test tanks new population is: 3 

<>< (Homer, red Guppy) <>< (Marge, blue Cichlid) <>< (Bart, yellow Tetra) 

The test tank contains 1 Cichlid(s). The test tank contains 1 Guppy (or Guppies). The test tank contains 1 Tetra(s). The test tank contains 0 Mollie(s). 

CSE 101 Fall 2018 Lab #8 Page 3

Creating a new 15-gallon aquarium from tank1.txt... tank1 contains 12 fish: 

<>< (Alvin, orange Tetra) <>< (Simon, gray Guppy) <>< (Theodore, blue Oscar) <>< (Bart, yellow Cichlid) <>< (Lisa, green Barb) <>< (Homer, yellow Goldfish) <>< (Marge, red Gourami) <>< (Maggie, pink Mollie) <>< (Ned, gray Cichlid) <>< (Maude, orange Barb) <>< (Krusty, white Gourami) <>< (Bob, green Cichlid) 

Creating a new 30-gallon aquarium from tank2.txt... tank2 contains 20 fish: 

<>< (Zippy, yellow Barb) <>< (Sparky, green Goldfish) <>< (Itchy, white Barb) <>< (Scratchy, black Cichlid) <>< (Manny, green Mollie) <>< (Moe, yellow Gourami) <>< (Jack, white Gourami) <>< (Dexter, blue Goldfish) <>< (Rob, black Gourami) <>< (Eddie, yellow Tetra) <>< (Jesse, gray Mollie) <>< (Dave, gray Cichlid) 

<>< (Danny, yellow Guppy) <>< (Billy, yellow Gourami) <>< (Mary, gray Mollie) <>< (Sue, red Oscar) <>< (Barbara, yellow Mollie) <>< (Dinah, orange Oscar) <>< (Ellen, gray Oscar) <>< (Joan, yellow Guppy) 

Creating a new 10-gallon aquarium from tank3.txt... tank3 contains 10 fish: 

<>< (Mario, black Tetra) <>< (Luigi, white Mollie) <>< (Peach, orange Guppy) <>< (Toad, red Guppy) <>< (Bowser, yellow Mollie) <>< (Koopa, black Barb) <>< (Link, black Gourami) <>< (Zelda, green Mollie) <>< (Luke, orange Cichlid) <>< (Leia, red Tetra)