CPSC150A
Scientific Computing

Stock Bots

• Automated Trading System - 75% of stock trades are bots
• Crash of 2:45

Practice Session

• Saturday at 5PM in Trexler 363
• CS subject tutor will give you practice problems answer any questions you have

Reading Questions

Quiz

Modules

• 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.')

• Save it as import_me.py

• 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

Math Module

• 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

Random Module

• 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?

Activity