Python List Functions: Pop and Insert

Overview of List Functions

• Python lists have functions to insert or remove values.
• Functions discussed:
  • pop: Removes and returns an element.
  • insert: Inserts a new value at a specified index.
• Both functions permanently modify the list (destructive functions) just like append and extend.

Pop Function

• Purpose: Removes and returns the element at the specified index.
• Behavior:
  • If no index is specified, the last element is removed and returned.
  • After popping, the list length is reduced by one.
  • Elements to the right of the specified index shift one position to the left.
• Usage Example:
  • Popping at index 0 removes the first element and shifts other elements left.
  • Attempting to pop at an out-of-range index results in an IndexError.

Insert Function

• Purpose: Inserts a new value at a specified index.
• Behavior:
  • The list length increases by one.
  • Values at and after the specified index shift one position to the right.
• Usage Example:
  • Inserting foo at index 0 shifts existing elements to the right.
  • Inserting at the list's length is equivalent to using append.
  • If the index is larger than the list's length, the value is appended at the end.

Practical Demonstration

• List Example: [2, 4, 6, 8, 10]
• Creating References:
  • Both A and C point to the same list, demonstrating shared changes.
• Pop Operations:
  • Pop without parameters removes 10 which was at the end.
  • Pop at index 0 removes 2, shifting other elements.
• Insert Operations:
  • Insert foo at index 0 shifts existing elements to accommodate the new element.
  • Inserting bar at the end appends it without shifting other elements.
  • Inserting using an out-of-range index appends bar at the end.