Questions
How can I define new functions?
What’s the difference between defining and calling a function?
What happens when I call a function?
Objectives
Define a function that takes parameters.
Return a value from a function.
Set default values for function parameters.
Document our functions.
Explain why we should divide programs into small, single-purpose functions.
Lecture
VIDEO
Alternate video link .
Jupyter Notebook File
Please use the Jupyter notebook named "07CreatingFunctions.ipynb " for this lesson. If you haven't downloaded them already, you may find them here .
Key Points
Define a function using def function_name(parameter)
.
The body of a function must be indented.
Call a function using function_name(value)
.
Numbers are stored as integers or floating-point numbers.
Variables defined within a function can only be seen and used within the body of the function.
If a variable is not defined within the function it is used, Python looks for a definition before the function call
Use help(thing)
to view help for something.
Put docstrings in functions to provide help for that function.
Specify default values for parameters when defining a function using name=value
in the parameter list.
Parameters can be passed by matching based on name, by position, or by omitting them (in which case the default value is used).