MACS 401 Exam 1

Namespace

a collection of names and their associated objects or mapping between variable names and python object (like a dictionary)

• can change depending on where you are in your program

• can store names of variables, functions and classes

• currently defined symbolic names and information about an object

Variable

pointers that "point" to objects.

• flag or name of an area of memory (‘object’)

Class

like an object constructor, or a "blueprint" for creating objects

• Objects have different attributes and respond in different ways to built-in functions

• Can be used to store information

• Certain names or identifiers can never be used (False, else, if, etc… has its own meaning)

Data Types/Classes

• float - a real number w/ a fractional part

• int - used for integers.

• str - used for texts. We can define strings using single, double, or triple quotes. They’re also used for writing function documentation.

• bool - used for truth/false values. Useful to perform a filtering operation on a data.

• list - used to store a collection of values.

• dict - used to store a key-values pairs.

• complex - complex number such as 5i

List

an ordered, changeable sequence or data structure. Use when order matters and you'll add, remove, or reorder items.

• numbers = [1, 2, 3]

• Lists are not meant for math! They don’t have a datatype.

Tuple

an ordered sequence that can't be changed after creation. Good for fixed groupings like coordinates

• raw_data = (1, 2, 3)

• point(3, 4)

Index

the numerical position of an item within an ordered sequence, such as a list, string, tuple, or range

• my_list[0][1] with the “0” being the item in the list and the “1” being the position of the letter/number in the item

• negative indexing exists, with -1 referring to the last letter/number in a term

• python counts from ZERO

Inclusivity

Python is left-inclusive and right-exclusive when using ranges and slicing.

How It Works

• Left side (Start): Included in the result.

• Right side (Stop): Excluded from the result.

Conditionals

if and while statements

• also elif, else, for

Comparison Operators

a symbol that allows you to compare two values and return a Boolean result: either True or False

== equal to

!= not equal to

< less than

> greater than

>= greater than or equal to

<= less than or equal to

and

or

Loop

programming construct that allows a block of code to be executed repeatedly until a certain condition is met

• Iterates over any iterable — list, string, range, tuple, dict, file, etc.

• range(n) generates numbers 0 to n−1

• for i in range (5) = 0, 1, 2, 3, 4

• break exits early, continue skips to the next item

Functions

a piece of reusable code solving a specific task

• can create functions using: def function_name()

• can be created or built in already to python

• take some inputs (“arguments”) and do something in response

Methods

function that is available for a given object depending on the object’s type.

Data Structures

a way of organizing and storing data so you can access and change it efficiently, may have specific operators that work on them.

• ex) Int, Float, Str, Lists, Tuples

Boolean Logic

a form of algebra where all variables and values are strictly limited to one of two states: true (1) or false (0)

Dictionaries

maps keys to values, unordered

• d = {‘name’: ‘Ryan’, ‘number’: 2}

• d = dict(name='Takaya', age=25)

• to access a value type: d['name']

Pure function

Functions that don’t modify their arguments or produce any other side-effects

Impure function

Functions that modify their arguments or cause other actions to occur

Magic/dunder method

special methods that begin with double-underscores, which allow us to customize the behavior of our classes.

Slicing

• The first character has index 0

• Slice To the End: print(b[2:])

  • Get the characters from position 2, and all the way to the end

• Slice From the Start: print(b[:5])

  • Get the characters from the start to position 5 (not included)