Comp Sci Final

Python Data Structures

-built in non primitive structures: list, tuple, set, dictionary

-used to store and organize collections of data

-choice dpeends on mutabilty, order, and uniqueness

Lists

-ordered, mutable, allows duplicates

-can store mixed data type and nested lists

List concepts

-indexing (positvie and negative)

-slicing creates a new list

-slice assignment modifies a list in place

-lists are passed by refernece to functions

List common methods

-append(0, extend(), insert()

-pop(), remove(), clear()

-sort(), reverse()

Aliasing

• b=a both refernce the same list

-changes to one affect the other

-use slicing ( a[ :] ) to copy safely

Tuples

-ordered and immutable

-allow duplicates

-faster and more memory-efficient than lists

Tuple Rules

-single element tuple needs a comma: (5, )

-cannot add/remoce elements (immutable)

-can modify mutiable elements inside a tuple

Tuple Operatiosn

-concatenation + and repetition *

-tuple unpacking: a, b = b, a

-sorted() returns a list, NOT a tuple

Sets

-unordered

-no duplicates

-no indexing

Sets Operations

-add(), update()

-remove()

-discard()

Set math

union, interaction, difference

Set use cases

remove duplicates, membership testing, mathematical set operations

File Handling Open methods

“r” read

“w” write (overwrite)

“a” append

“r+”, “w+”, “a+”

“b” binary, “t” text (default)

Reading & Writing

-read(), readline(), deadlines()

-write(), writelines()

-ALWAYS include \n for new lines

JSON Serialization

-convert python objects to string

-used heavily with APIs

json.dumps()

serialize

json.loads()

deserialize

Serialization

converting python object (like dictionary or list) into a JSON-formatted string

APIs

requests library

Status codes

200 OK, 400 Bad request, 401 Unauthorized, 403 Forbidden, 404 Not found, 503 Service unavailable

Returned Data

-usually dictionaries

-access via keys

Core OOP Concepts

-class: blueprint

-object: instance

-attributes: data

-methods: behavior

self.

refers to the object

instance attributes

belong to each object

class attributes

shared by all objects

encapsulation

-access data via methods (get or set)

-protect internal state

inheritance

-child class inherits from parent

overriding

child replaces parent method/attribute

super()

reuse parent methods

Inheritance types

-single

-multilevel

-multiple inheritiance

NumPy

-fast numerical arrays

-fixed size, same data type

NumPy Array creation

-np.array()

-np.zeros(), np.ones()

-np.arange(), np.linspace()

NumPy Indexing

similar ot lists

-multi-dimensional: a[row, col]

-boolean indexing is common on exams

NumPy Operations

-element-wise math

-statisitcal functions: mean, std, max, min

Pandas Series

-one dimensional labeled data

-like a column

Pandas Data Frame

-two dimensional table

-rows and columns

Pandas Indexing

df [ col ]

df.loc [ label ]

df.iloc [ index ]

-boolean filters

Visualization

-uses NumPy + Pandas data

-typically wiht matplotlib

-often paired with statiscal analysis

False

bool ( 0 ), ( 0, 0 ), ( “ “ ), ( None )

for loop

-iterates over knwon sequence

-ex: list, range, string

while loop

-runs until a condition change

-used when number of iterates is unknown

%

finds division remainder

//

integer divsion so must be whole number output

Why is range(5, 10, 0.5) incorrect

can NOT hvae float numbers in a range ONLY integers

continue

-skips remaining code in the loop

-immediately jumps to the next iteration

comments

-python ignores

-only exist for humans

and

need both to be True to return True

or

True if at least one operand is True

Natural Languages

change and evolve

Formal Language

strict fixed rules

==

equals

!=

not equal

case_:

-matches anything not previously matched

-acts like else

interpreter

-python executes code line by line

-no full compilation step

XOR operator (ex: 1011 ^ 0111)

same = 0

diff = 1

What happens if you hvae a return statment in a Python function with no value following

implicit return value is None

AND operator (ex: 110101 & 101010)

returns 1 if both 1

returns 0 if one is 0

pass

-placeholder

-does nothing

-prevents syntax erros for empty blocks

upper()

makes the string all uppercase

[::-1]

reverses

.find()

returns the starting index of the term

spilt()

spilts on any white space

-returns a list of words

iterations are more efficient

than recursion

s.clear()

removes all items from a set

pop()

removes the last element