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STAT 404 - MIDTERM 2 Terms in this set (44) Why do we need functions? Data structures tie related values into one object Functions tie related commands into one object In both cases: easier to understand, easier to work with, easier to build int€5,64
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STAT 404 - MIDTERM 2 Terms in this set (44) Why do we need functions? Data structures tie related values into one object Functions tie related commands into one object In both cases: easier to understand, easier to work with, easier to build int
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STAT 404 - MIDTERM 2
Terms in this set (44)
Why do we need functions? Data structures tie related values into one object Functions tie related commands into one object
In both cases: easier to understand, easier to work with, easier to build into larger things
Function struc...
Data structures tie related values into one object
Functions tie related commands into one object
Why do we need functions?
In both cases: easier to understand, easier to work with, easier to build into larger
things
The structure of a function has three basic parts:
Function structure
- Name Inputs (or arguments): what should a user provide to the function?
- Arguments
- Body Body: code that is executed
- Return
Output (or return value): what is the side effect of your function
Things you're going to re-run, especially if it will be re-run with changes to arguments
What should be a function? Chunks of code which are small parts of bigger analyses
Chunks of code which are very similar to other chunks1
Test code outside a function first
Put code in a function and test
Best practices when creating a function Replace hard coded values with arguments and test again
Use parenthesis liberally
Only include in the function what can be repeate
With no explicit return() statement, the default is just to return whatever is on the last
What is the default return value?
line
A function can also specify default values for the inputs (if the user doesn't specify an
How and when to use default inputs
input in the function call, then the default value is used)
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, 8/3/24, 2:01 PM
Inputs can be called by name, or without
Calling functions we define works just like Inputs can be called by partial names (if uniquely
calling built-in functions: named arguments,
default. When inputs aren't specified, default values are
Named inputs can go in any order
While named inputs can go in any order, unnamed inputs must go in the proper order
(as they are specified in the function's definition).
How are argument values matched to
arguments when a function is called?
When calling a function with multiple arguments, use input names for safety, unless
you're absolutely certain of the right order for (some) inputs10
When creating a function in R, though you cannot return more than one output, you
How to return more than one output
can return a list. This (by definition) can contain an arbitrary number of arbitrary objects
A side effect of a function is something that happens as a result of the function's body,
but is not returned.Examples:
Printing something out to the console
What is a side effect?
Plotting something on the display
Saving an R data file, or a PDF, etc.
Interfaces mark out a controlled inner environment for our code
Interact with the rest of the system only at the interface
Interfaces control what the function can see
(arguments, environment) and change (its Advice: arguments explicitly give the function all the information
internals, its return value) - Reduces risk of confusion and error
- Exception: true universals like π
Likewise, output should only be through the return value
In R, functions are objects, just like everything else
What do we mean by functions are objects?
This means that they can be passed to functions as arguments and returned by
functions as outputs as well
Beyond regular functions, we can use
Functionals: functions that take another function as
an argument (like the apply family). Most likely to
use
What are the four higher order classifications
of functions?
Function factories: functions that create functions
(like ecdf()). Less common.
Function operators: functions that take functions as
input and output a function
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