The list.extend() method in Python is used to add multiple elements to the end of a list. Unlike list.append(), which adds a single element, extend() takes an iterable (such as a list, tuple, or string) and appends each of its elements to the original list. This method modifies the original list in place and does not return a new list.

Syntax

list.extend(iterable)

• Parameters:
  • iterable: An iterable (like a list, tuple, set, or string) whose elements will be added to the list.

Return Value

• The method does not return a value (None is returned implicitly).

Example Usage

1. Extending a List with Another List:

   my_list = [1, 2, 3]
   my_list.extend([4, 5, 6])  # Extending with another list
   print(my_list)  # Output: [1, 2, 3, 4, 5, 6]
   

2. Extending with a Tuple:

   my_list = ['a', 'b']
   my_list.extend(('c', 'd', 'e'))  # Extending with a tuple
   print(my_list)  # Output: ['a', 'b', 'c', 'd', 'e']
   

3. Extending with a String: When extending with a string, each character of the string is added as a separate element:

   my_list = ['x', 'y']
   my_list.extend('z')  # Extending with a string
   print(my_list)  # Output: ['x', 'y', 'z']
   

4. Using extend() in a Loop: You can also use extend() to add elements from an iterable dynamically:

   my_list = []
   for i in range(5):
       my_list.extend([i])  # Extending with a list containing the current integer
   print(my_list)  # Output: [0, 1, 2, 3, 4]
   

5. Combining Lists: You can use extend() to combine two lists:

   list1 = [1, 2]
   list2 = [3, 4]
   list1.extend(list2)  # Extending list1 with list2
   print(list1)  # Output: [1, 2, 3, 4]
   

Summary

• list.extend() is a powerful method for adding multiple elements to a list from any iterable.
• It modifies the original list in place and allows for the combination of various data types.
• This method is particularly useful when you want to merge lists or append multiple elements at once without nesting them in a new list.