Lecture 3: Functions and Modules

"import" command

allows one to access a module (you use module as prefix to a function afterwards, e.g. math.cos(math.pi))

"from" keyword

allows one to use certain functions without having to use module as prefix; however, using import is safer overall

argument

any expression inside a function

module data

(dc definition?) functions that exist within a module

function call vs function definition

1) both are commands to do the function, difference is where they can be placed. function call can be placed anywhere -- in python shell, or inside another module, while function definitions belong inside a module 2) function calls can be called as many times as you want, while you can only define a function once.

module vs script

1) modules are imported (e.g. "import module"), while scripts are run from command line (e.g. python helloApp.py). 2) modules provide functions and variables, while scripts behave like applications. 3) when you run a script, only statements/commands are executed. need to use print() function to display values in scripts; while modules will automatically display values (ask for clarification?) *files look the same but the difference is how you use them*

single line comment

denoted by #, not executed by python

docstring

denoted by triple quotes, acts as multiple-line comment; good for code documentation

print(exp)

displays value of exp (expression) on screen

commands

executed after importing a module; "import" will ignore non-commands

module

file that contains python code; way for python to provide optional functions

interactive shell vs module

for interactive shell, python executes each line separately as you type, while for modules you write them in a code editor (e.g. Atom Editor) and then load into python with "import"

function call

function in an expression

in the example fun(x), fun is the ___ and (x) is the ___

function name; argument

built-in function

function that does not need to be imported in python as it already exists; very few of them in python

help()

help function

other modules

io (read/write from files), random (generate random numbers, can pick any distribution), string (useful string functions), sys (information about OS)

help(module)

prints doctoring and module contents

quit()

quit function

input("Type something ")

will prompt user to type something; value returned is a string, even if it looks like int. other values, such as int(), float(), bool(), etc must be converted in order to be used, not a good way to program

modules must be in ___

working directory; must navigate to folder before running python