7 List Functions Every Python Programmer Should Know

1. len(list)

   This function returns the length (number of items) of a list.

   
   my_list = [1, 2, 3, 4, 5]
   list_length = len(my_list)
   print(list_length)  # Output: 5
               

2. append(item)

   This method adds a new item to the end of a list.

   
   fruits = ["apple", "banana", "cherry"]
   fruits.append("orange")
   print(fruits)  # Output: ["apple", "banana", "cherry", "orange"]
               

3. extend(iterable)

   This method adds all the items from an iterable (like another list or a tuple) to the end of the existing list.

   
   numbers = [1, 2, 3]
   more_numbers = [4, 5, 6]
   numbers.extend(more_numbers)
   print(numbers)  # Output: [1, 2, 3, 4, 5, 6]
               

4. index(item)

   This method returns the index (position) of the first occurrence of an item in the list. If the item is not found, it raises a ValueError.

   
   colors = ["red", "green", "blue", "green"]
   first_green_index = colors.index("green")
   print(first_green_index)  # Output: 1
               

5. sort(reverse=False)

   This method sorts the items of a list in place. By default (reverse=False), it sorts in ascending order. You can optionally set reverse=True for descending order.

   
   my_list = [3, 1, 4, 5, 2]
   my_list.sort()  # Sorts the list in place
   print(my_list)  # Output: [1, 2, 3, 4, 5]
               

6. insert(index, item)

   This method inserts an item at a specified index in the list.

   
   weekdays = ["Monday", "Wednesday", "Friday"]
   weekdays.insert(1, "Tuesday")  # Insert Tuesday at index 1
   print(weekdays)  # Output: ["Monday", "Tuesday", "Wednesday", "Friday"]
               

7. remove(item)

   This method removes the first occurrence of a specified item from the list. If the item is not found, it raises a ValueError.

   
   vegetables = ["carrot", "potato", "carrot", "broccoli"]
   vegetables.remove("carrot")  # Removes the first carrot
   print(vegetables)  # Output: ["potato", "carrot", "broccoli"]