CPSC120B - Day 7 Notes

We already know how to use modules, we’ve been using them since the first Python program you created
When you add import turtle to the top of a file it allows you to use functions that begin with turtle dot something
It allows you to use code that someone else wrote

For example write a program like the following

pi = 3.14159
print('I created the variable pi.')

Create another program

import import_me
print('I imported the variable pi.')
print('And now I can print it.'
print(import_me.pi)

Importing another pythong file, executes all of the code in it
This includes creating any of the variables that are defined in it as well as any of the functions in it
We haven’t learned how to define our own functions yet, but you have used functions that you have imported with turtle, turtle.forward(100), for example
Note, that to use the variable in the module, it must be prefixed with the name of the module
This is why all the turtle functions start with turtle.
This is also why you can’t name a file the same thing as one of the modules you are importing

One useful module is the math module, which gives you functions like math.sin, math.cos, math.log
In addition to functions, modules can have variable you can use
The math module has math.pi so you don’t have create a constant

Another useful module is the random module, which give you functions to generate pseudo-random numbers
The random.random function gives random numbers in the range [0.0, 1.0) (note that is exclusive of 1.0)
The random.randrange function give random integers in the specified range (note the upper bound is exclusive)
The probablity distribution of both random functions is flat
What if you want to create a floating point number in a range?

CPSC120B
Fundamentals of Computer Science