Build-in Methods in List

Lists are ordered collections of items, and these methods allow for various operations such as adding, removing, or modifying elements, among others.

Here’s a rundown of common built-in methods for working with lists:

1.append(item)

Adds a single item to the end of the list.

Example:

my_list = [1, 2, 3] 
my_list.append(4) # List becomes [1, 2, 3, 4]

2. extend(iterable)

Extends the list by appending all elements from the iterable (e.g., another list, tuple, etc.).

Example:

my_list = [1, 2, 3] 
my_list.extend([4, 5, 6]) # List becomes [1, 2, 3, 4, 5, 6]

3. insert(index, item)

Inserts an item at a specified position in the list.

Example:

my_list = [1, 2, 3] 
my_list.insert(1, 'a') # List becomes [1, 'a', 2, 3]

4. remove(item)

Removes the first occurrence of an item in the list. If the item is not found, it raises a ValueError.

Example:

my_list = [1, 2, 3, 2] 
my_list.remove(2) # List becomes [1, 3, 2]

5. pop([index])

Removes and returns the item at the specified index. If no index is provided, it removes and returns the last item.

Example:

my_list = [1, 2, 3] 
my_list.pop() # Returns 3, list becomes [1, 2] my_list.pop(0) # Returns 1, list becomes [2]

6. clear()

Removes all items from the list, resulting in an empty list.

Example:

my_list = [1, 2, 3] 
my_list.clear() # List becomes []

7. index(item, start=0, end=len(list))

Returns the index of the first occurrence of the specified item. Optionally, you can provide a start and end range to search within.

Example:

my_list = [1, 2, 3] 
my_list.index(2) # Returns 1

8. count(item)

Returns the number of times the specified item appears in the list.

Example:

my_list = [1, 2, 2, 3] 
my_list.count(2) # Returns 2

9. sort(key=None, reverse=False)

Sorts the list in ascending order by default. You can pass a key function to customize sorting and use reverse=True to sort in descending order.

Example:

my_list = [3, 1, 2] 
my_list.sort() # List becomes [1, 2, 3] 
my_list.sort(reverse=True) # List becomes [3, 2, 1]

10. reverse()

Reverses the elements of the list in place.

Example:

my_list = [1, 2, 3] 
my_list.reverse() # List becomes [3, 2, 1]

11. copy()

Returns a shallow copy of the list.

Example:

my_list = [1, 2, 3] 
new_list = my_list.copy() # new_list becomes [1, 2, 3]

12. list()

Converts an iterable (such as a string or tuple) to a list.

Example:

my_tuple = (1, 2, 3) 
new_list = list(my_tuple) # new_list becomes [1, 2, 3]