Lecture 6

Lecture 6, Tue 04/22

Deriving Big-O and Algorithm Analysis, Recursion

Announcments

Last of the slower days. Hw01 and Lab01 are due tonight! Labs and homework are always due each week on Tuesday at midnight.
The homeworks relate to the corresponding chapters and sections of the textbook that are explicitly stated on the lecture slides.
Electronic version is not the official version and sometimes crashes.
The inheritance section of the textbook explains that it allows us to use the methods of a parents class.
We need to visualize and understand where python will jump in its execution.
While the fraction class is easy to understand, the example is slightly harder to understand if you do not run through the example yourself.
Try using python tutor, it is highly recommended and very efficient. It allows you to walk through the steps one at a time and provides a visual as well.
Make sure you have a mental picture of what is going on with the code before you start coding.
This will provide you with a much better understanding when jumping into the labs.

Any other attributes?
- Perm number, distance from campus.
What does it mean to have a standard method?
- __str__ is a standard methods provided to you by python.
What would be a potential advantage of providing our own constructor?
- Student jumping ahead: “It gives us control over how the object is initialized, and if another class inherits from it, the child class can also inherit that initialization.”
- Another student answered: “More convienet to initialize an object of that class with all of the attributes we have already defined.”
- When we have constructor, we are batch-creating all of the attruutes we want the object to have.
- Creates a container that is consisent across all of the objects of that class.
What does a getter method do?
- Student answered: “Return the value of whatever it is in charge of getting.”
What input does it need?
- No input is necesary, since it returns a value.

What does any method need as its first parameter?
- self
How do I represent the fact that I am comparing two objects?
- Student answered: “You need the other object as an argument”
Need to return the result that I am comparing?
- Yes, the result of comparing two PERM numbers
What other operators exist?
- Addition
- Comparison
How do we compare two objects by the year instead?
- Replace name.upper with year
How do we compare two objects by the year in addition to the name?
- Student answered: Use (this == this) and (this == this) meaning return self.name == other.name and self.year == other.year
- other has to be an object of the same class or python will throw an attribute error