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Types of Data Structures/Sequences

- container#1: Lists 
- container#2: Tuples 
- container#3: Sets 
- container#4: Dictionaries

docs by python.org

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Container - List

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• are ordered, an ordered collection of items/objects (an innate characteristic of the list).
  • the items have a defined order,
  • that order will not change.
  • lists with the same elements in a different order are not the same.
• are sequences of elements of any type (like complex objects)
  • Functions
  • Classes
  • Module
• may contain any number of elements/objects (constrained by the computer’s memory, of course), of any type(can store heterogeneous data types).
• Does not to be unique: same object may occur any number of times.
• are mutable, meaning you can add, remove, or modify elements in place.

Common sequence operations

• len(sequence)
  • Returns the length of the sequence
• using in to verify if the sequence contains an element. 
• for element in sequence
  • Iterates over each element in the sequence
• if element in sequence
  • Checks whether the element is part of the sequence
• sequence[i]
  • Accesses the element at index i of the sequence, starting at zero
• sequence[i:j]
  • Accesses a slice starting at index i, ending at index j-1. If i is omitted, it’s 0 by default. If j is omitted, it’s len(sequence) by default.
• for index, element in enumerate(sequence)
  • Iterates over both the indexes and the elements in the sequence at the same time
• iterating over them using for-loops, 
• using plus to concatenate two sequences

Ordered example

[1, 2, 3, 4] == [4, 1, 3, 2]
False
a = ['spam', 'egg', 'bacon', 'tomato']
b = ['egg', 'bacon', 'tomato', 'spam']

a == b
False
a is b
False

Access example

months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December']

print(months[-1]) # December
print(months[25]) # IndexError: list index out of range

q3 = months[6:9]
print(q3) # [ 'July', 'August', 'September']
first_half = months[:6]
print(first_half) # ['January', 'February', 'March', 'April', 'May', 'June']
second_half = months[6:]
print(second_half) # ['July', 'August', 'September', 'October', 'November', 'December']

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in OR not in

'this' in 'this is a string'
# True
5 not in [1, 2, 3, 4, 6]
# True
5 in [1, 2, 3, 4, 6]
# False

x = ["This", "is", "a", "list"]
"Today" in x
    #OUTPUT
    False
#"This" in list would return True.

pop() method 

• list.pop(i)
• remove elements
• method receives an index.
• returns the element that was removed at the index that was passed.
• to change an item by assigning something else to that position, 

fruits = ["Orange", "Pineapple", "Banana", "Apple"]
fruits.pop(3)
print(fruits)
["Orange", "Pineapple", "Banana"]

index() method 

• list.index([,[, ]])

li = ['a', 'b', 'c', 'b']
li.index('b') # index of first occurrence*
# OUTPUT
1

count() method 

• list.count()

li.count('b') # number of occurrences
2

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Container - Tuples

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• similar to lists but are immutable, meaning they cannot be modified once created.
• used to represent fixed collections of related data.
  • are sequences of elements of any type
  • are immutable.

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Container - Dictionaries

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• are key-value pairs and provide a way to store and retrieve data based on a unique key.
• also known as associative arrays or hash maps.
• are useful for mapping one value to another and are highly efficient for data retrieval.

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Container - Sets

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• unordered collections of unique elements.
• to eliminate duplicate values or perform set operations such as union, intersection, or difference.

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Data Structure
Lists
List methods
Tuples
Dictionary
Dictionary methods
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