Python Lists

Lists

• Ordered collection of items
• Can contain duplicates
• Can be indexed and sliced
• Mutable (can be modified)
• Can be created using square brackets [] or the list() function
• Methods:
  • append(): adds an item to the end of the list
  • extend(): adds multiple items to the end of the list
  • insert(): inserts an item at a specific position
  • remove(): removes the first occurrence of an item
  • sort(): sorts the list in ascending order
  • reverse(): reverses the order of the list

Sets

• Unordered collection of unique items
• No duplicates allowed
• Mutable (can be modified)
• Can be created using curly braces {} or the set() function
• Methods:
  • add(): adds an item to the set
  • remove(): removes an item from the set
  • discard(): removes an item from the set if it exists
  • union(): returns a new set with all items from two sets
  • intersection(): returns a new set with items common to two sets
  • difference(): returns a new set with items in one set but not the other

Dictionaries

• Unordered collection of key-value pairs
• Each key is unique
• Values can be of any data type
• Mutable (can be modified)
• Can be created using curly braces {} or the dict() function
• Methods:
  • keys(): returns a view object of all keys
  • values(): returns a view object of all values
  • items(): returns a view object of all key-value pairs
  • get(): returns the value for a given key
  • update(): updates the dictionary with new key-value pairs

Strings

• Sequence of characters
• Immutable (cannot be modified)
• Can be created using quotes ' or ", or the str() function
• Methods:
  • upper(): returns a new string with all characters uppercase
  • lower(): returns a new string with all characters lowercase
  • strip(): removes leading and trailing whitespace
  • split(): splits the string into a list of substrings
  • join(): joins a list of strings into a single string

Tuples

• Ordered collection of items
• Immutable (cannot be modified)
• Can be created using parentheses () or the tuple() function
• Methods:
  • index(): returns the index of the first occurrence of an item
  • count(): returns the number of occurrences of an item

Lists

• Ordered collections of items that can contain duplicates and be indexed and sliced.
• Can be created using square brackets [] or the list() function.
• Lists are mutable, meaning they can be modified.
• Methods for modifying lists include:
  • append() to add an item to the end of the list.
  • extend() to add multiple items to the end of the list.
  • insert() to insert an item at a specific position.
  • remove() to remove the first occurrence of an item.
  • sort() to sort the list in ascending order.
  • reverse() to reverse the order of the list.

Sets

• Unordered collections of unique items, meaning no duplicates are allowed.
• Sets are mutable, meaning they can be modified.
• Can be created using curly braces {} or the set() function.
• Methods for modifying sets include:
  • add() to add an item to the set.
  • remove() to remove an item from the set.
  • discard() to remove an item from the set if it exists.
• Set operations include:
  • union() to return a new set with all items from two sets.
  • intersection() to return a new set with items common to two sets.
  • difference() to return a new set with items in one set but not the other.

Dictionaries

• Unordered collections of key-value pairs, where each key is unique.
• Values can be of any data type.
• Dictionaries are mutable, meaning they can be modified.
• Can be created using curly braces {} or the dict() function.
• Methods for accessing and modifying dictionaries include:
  • keys() to return a view object of all keys.
  • values() to return a view object of all values.
  • items() to return a view object of all key-value pairs.
  • get() to return the value for a given key.
  • update() to update the dictionary with new key-value pairs.

Strings

• Sequences of characters that are immutable, meaning they cannot be modified.
• Can be created using quotes ' or ", or the str() function.
• Methods for modifying strings include:
  • upper() to return a new string with all characters uppercase.
  • lower() to return a new string with all characters lowercase.
  • strip() to remove leading and trailing whitespace.
  • split() to split the string into a list of substrings.
  • join() to join a list of strings into a single string.

Tuples

• Ordered collections of items that are immutable, meaning they cannot be modified.
• Can be created using parentheses () or the tuple() function.
• Methods for accessing tuples include:
  • index() to return the index of the first occurrence of an item.
  • count() to return the number of occurrences of an item.

Learn about the characteristics and methods of lists in Python, including indexing, slicing, and mutability.