python data structure

Here’s a cheat sheet for Lesson 3: Data Structures in [[Python Intro]]:

Lists:

• Definition: Ordered collection of items.
• Creation: Using square brackets [].
• Indexing: Accessing elements by their position.
• Slicing: Extracting a subset of elements.
• Methods: Built-in functions to manipulate lists.
  • append(): Adds an element to the end.
  • insert(): Inserts an element at a specified position.
  • remove(): Removes the first occurrence of a value.
  • pop(): Removes and returns the element at a specified index.
• Example:

my_list = [1, 2, 3, 4, 5]
print(my_list[0])    # Output: 1
print(my_list[1:3])  # Output: [2, 3]
my_list.append(6)
print(my_list)       # Output: [1, 2, 3, 4, 5, 6]

Tuples:

• Definition: Ordered, immutable collection of items.
• Creation: Using parentheses ().
• Accessing Elements: Similar to lists, using indexing.
• Example:

my_tuple = (1, 2, 3)
print(my_tuple[0])   # Output: 1

Dictionaries:

• Definition: Unordered collection of key-value pairs.
• Creation: Using curly braces {}.
• Accessing Values: Using keys.
• Methods:
  • keys(): Returns a list of all keys.
  • values(): Returns a list of all values.
  • items(): Returns a list of key-value tuples.
• Example:

my_dict = {'a': 1, 'b': 2, 'c': 3}
print(my_dict['a'])          # Output: 1
print(my_dict.keys())        # Output: dict_keys(['a', 'b', 'c'])
print(my_dict.values())      # Output: dict_values([1, 2, 3])

Notes:

• Lists and dictionaries are mutable, meaning they can be modified after creation.
• Tuples are immutable, meaning they cannot be modified after creation.
• Lists are used for sequential data, tuples for fixed collections, and dictionaries for key-value mappings.