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In Python, lists are versatile mutable sequences with built-in methods for adding, removing, searching, sorting, and more—covering all common scenarios like dynamic data manipulation, queues, or stacks. Below is a complete breakdown of all list methods, each with syntax, an example, and output, plus key built-in functions for comprehensive use.
📚 Adding Elements
⦁ append(x): Adds a single element to the end.
lst = [1, 2]
lst.append(3)
print(lst) # Output: [1, 2, 3]
⦁ extend(iterable): Adds all elements from an iterable to the end.
lst = [1, 2]
lst.extend([3, 4])
print(lst) # Output: [1, 2, 3, 4]
⦁ insert(i, x): Inserts x at index i (shifts elements right).
lst = [1, 3]
lst.insert(1, 2)
print(lst) # Output: [1, 2, 3]
📚 Removing Elements
⦁ remove(x): Removes the first occurrence of x (raises ValueError if not found).
lst = [1, 2, 2]
lst.remove(2)
print(lst) # Output: [1, 2]
⦁ pop(i=-1): Removes and returns the element at index i (default: last).
lst = [1, 2, 3]
item = lst.pop(1)
print(item, lst) # Output: 2 [1, 3]
⦁ clear(): Removes all elements.
lst = [1, 2, 3]
lst.clear()
print(lst) # Output: []
📚 Searching and Counting
⦁ count(x): Returns the number of occurrences of x.
lst = [1, 2, 2, 3]
print(lst.count(2)) # Output: 2
⦁ index(x[, start[, end]]): Returns the lowest index of x in the slice (raises ValueError if not found).
lst = [1, 2, 3, 2]
print(lst.index(2)) # Output: 1
📚 Ordering and Copying
⦁ sort(key=None, reverse=False): Sorts the list in place (ascending by default; stable sort).
lst = [3, 1, 2]
lst.sort()
print(lst) # Output: [1, 2, 3]
⦁ reverse(): Reverses the elements in place.
lst = [1, 2, 3]
lst.reverse()
print(lst) # Output: [3, 2, 1]
⦁ copy(): Returns a shallow copy of the list.
lst = [1, 2]
new_lst = lst.copy()
print(new_lst) # Output: [1, 2]
📚 Built-in Functions for Lists (Common Cases)
⦁ len(lst): Returns the number of elements.
lst = [1, 2, 3]
print(len(lst)) # Output: 3
⦁ min(lst): Returns the smallest element (raises ValueError if empty).
lst = [3, 1, 2]
print(min(lst)) # Output: 1
⦁ max(lst): Returns the largest element.
lst = [3, 1, 2]
print(max(lst)) # Output: 3
⦁ sum(lst[, start=0]): Sums the elements (start adds an offset).
lst = [1, 2, 3]
print(sum(lst)) # Output: 6
⦁ sorted(lst, key=None, reverse=False): Returns a new sorted list (non-destructive).
lst = [3, 1, 2]
print(sorted(lst)) # Output: [1, 2, 3]
These cover all standard operations (O(1) for append/pop from end, O(n) for most others). Use slicing
lst[start:end:step] for advanced extraction, like lst[1:3] outputs ``.#python #lists #datastructures #methods #examples #programming