CPSC120B - Day 10 Notes

We already know how to use modules, we’ve been using them since the first day, turtle
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
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
Note the probablity distribution of both random functions is flat
What if you want to create a floating point number in a range?

So far we have created graphical programs using turtle
But turtle isn’t very good for creating animations
The underlying graphical system that turtle is built on is difficult to use
So I created a module to make creating animations easier
Using module that is not built-in requires an extra step
Before importing it, you have to put the module’s .py file in the same directory and the .py file that is using it.
The graphics module’s documentation has a link to the graphics.py file you can use during lab
To draw an oval use the draw_oval function, need to specify the x, y, width, and height
In turtle we used exitonclick function to keep the window open, the graphics module supports mouse interation so clicking doesn’t close the window
Use the mainloop function to keep the winow open
Note the coordinate system is different than turtle, (0, 0) is in the upper left and positive y is down
Can also change the outline, fill, and thickness
To create an animation, need to draw multiple times
Add a loop to draw multiple ovals, but they all get drawn very quickly
To add a delay, use the wait function