Cheat Sheet: Lists and Tuples

 List

Package/Method	Description	Code Example
append()	The `append()` method is used to add an element to the end of a list.	Syntax: 1 list_name.append(element) Example: 1 2 fruits = ["apple", "banana", "orange"] fruits.append("mango") print(fruits)
copy()	The `copy()` method is used to create a shallow copy of a list.	Example 1: 1 2 3 my_list = [1, 2, 3, 4, 5] new_list = my_list.copy() print(new_list) # Output: [1, 2, 3, 4, 5]
count()	The `count()` method is used to count the number of occurrences of a specific element in a list in Python.	Example: 1 2 3 my_list = [1, 2, 2, 3, 4, 2, 5, 2] count = my_list.count(2) print(count) # Output: 4
Creating a list	A list is a built-in data type that represents an ordered and mutable collection of elements. Lists are enclosed in square brackets [] and elements are separated by commas.	Example: 1 fruits = ["apple", "banana", "orange", "mango"]
del	The `del` statement is used to remove an element from list. `del` statement removes the element at the specified index.	Example: 1 2 3 my_list = [10, 20, 30, 40, 50] del my_list[2] # Removes the element at index 2 print(my_list) # Output: [10, 20, 40, 50]
extend()	The `extend()` method is used to add multiple elements to a list. It takes an iterable (such as another list, tuple, or string) and appends each element of the iterable to the original list.	Syntax: 1 list_name.extend(iterable) Example: 1 2 3 4 fruits = ["apple", "banana", "orange"] more_fruits = ["mango", "grape"] fruits.extend(more_fruits) print(fruits)
Indexing	Indexing in a list allows you to access individual elements by their position. In Python, indexing starts from 0 for the first element and goes up to `length_of_list - 1`.	Example: 1 2 3 4 5 my_list = [10, 20, 30, 40, 50] print(my_list[0]) # Output: 10 (accessing the first element) print(my_list[-1]) # Output: 50 (accessing the last element using negative indexing)
insert()	The `insert()` method is used to insert an element.	Syntax: 1 list_name.insert(index, element) Example: 1 2 3 my_list = [1, 2, 3, 4, 5] my_list.insert(2, 6) print(my_list)
Modifying a list	You can use indexing to modify or assign new values to specific elements in the list.	Example: 1 2 3 4 my_list = [10, 20, 30, 40, 50] my_list[1] = 25 # Modifying the second element print(my_list) # Output: [10, 25, 30, 40, 50]
pop()	`pop()` method is another way to remove an element from a list in Python. It removes and returns the element at the specified index. If you don't provide an index to the `pop()` method, it will remove and return the last element of the list by default	Example 1: 1 2 3 4 5 6 7 my_list = [10, 20, 30, 40, 50] removed_element = my_list.pop(2) # Removes and returns the element at index 2 print(removed_element) # Output: 30 print(my_list) # Output: [10, 20, 40, 50] Example 2: 1 2 3 4 5 6 7 my_list = [10, 20, 30, 40, 50] removed_element = my_list.pop() # Removes and returns the last element print(removed_element) # Output: 50 print(my_list) # Output: [10, 20, 30, 40]
remove()	To remove an element from a list. The `remove()` method removes the first occurrence of the specified value.	Example: 1 2 3 4 my_list = [10, 20, 30, 40, 50] my_list.remove(30) # Removes the element 30 print(my_list) # Output: [10, 20, 40, 50]
reverse()	The `reverse()` method is used to reverse the order of elements in a list	Example 1: 1 2 3 my_list = [1, 2, 3, 4, 5] my_list.reverse() print(my_list) # Output: [5, 4, 3, 2, 1]
Slicing	You can use slicing to access a range of elements from a list.	Syntax: 1 list_name[start:end:step] Example: 1 2 3 4 5 6 7 8 9 10 11 12 my_list = [1, 2, 3, 4, 5] print(my_list[1:4]) # Output: [2, 3, 4] (elements from index 1 to 3) print(my_list[:3]) # Output: [1, 2, 3] (elements from the beginning up to index 2) print(my_list[2:]) # Output: [3, 4, 5] (elements from index 2 to the end) print(my_list[::2]) # Output: [1, 3, 5] (every second element)
sort()	The `sort()` method is used to sort the elements of a list in ascending order. If you want to sort the list in descending order, you can pass the `reverse=True` argument to the `sort()` method.	Example 1: 1 2 3 4 my_list = [5, 2, 8, 1, 9] my_list.sort() print(my_list) # Output: [1, 2, 5, 8, 9] Example 2: 1 2 3 4 my_list = [5, 2, 8, 1, 9] my_list.sort(reverse=True) print(my_list) # Output: [9, 8, 5, 2, 1]

Dictionary

Package/Method	Description	Code Example
Accessing Values	You can access the values in a dictionary using their corresponding `keys`.	Syntax: 1 Value = dict_name["key_name"] Example: 1 2 name = person["name"] age = person["age"]
Add or modify	Inserts a new key-value pair into the dictionary. If the key already exists, the value will be updated; otherwise, a new entry is created.	Syntax: 1 dict_name[key] = value Example: 1 2 person["Country"] = "USA" # A new entry will be created. person["city"] = "Chicago" # Update the existing value for the same key
clear()	The `clear()` method empties the dictionary, removing all key-value pairs within it. After this operation, the dictionary is still accessible and can be used further.	Syntax: 1 dict_name.clear() Example: 1 grades.clear()
copy()	Creates a shallow copy of the dictionary. The new dictionary contains the same key-value pairs as the original, but they remain distinct objects in memory.	Syntax: 1 new_dict = dict_name.copy() Example: 1 2 new_person = person.copy() new_person = dict(person) # another way to create a copy of dictionary
Creating a Dictionary	A dictionary is a built-in data type that represents a collection of key-value pairs. Dictionaries are enclosed in curly braces `{}`.	Example: 1 2 dict_name = {} #Creates an empty dictionary person = { "name": "John", "age": 30, "city": "New York"}
del	Removes the specified key-value pair from the dictionary. Raises a `KeyError` if the key does not exist.	Syntax: 1 del dict_name[key] Example: 1 del person["Country"]
items()	Retrieves all key-value pairs as tuples and converts them into a list of tuples. Each tuple consists of a key and its corresponding value.	Syntax: 1 items_list = list(dict_name.items()) Example: 1 info = list(person.items())
key existence	You can check for the existence of a key in a dictionary using the `in` keyword	Example: 1 2 if "name" in person: print("Name exists in the dictionary.")
keys()	Retrieves all keys from the dictionary and converts them into a list. Useful for iterating or processing keys using list methods.	Syntax: 1 keys_list = list(dict_name.keys()) Example: 1 person_keys = list(person.keys())
update()	The `update()` method merges the provided dictionary into the existing dictionary, adding or updating key-value pairs.	Syntax: 1 dict_name.update({key: value}) Example: 1 person.update({"Profession": "Doctor"})
values()	Extracts all values from the dictionary and converts them into a list. This list can be used for further processing or analysis.	Syntax: 1 values_list = list(dict_name.values()) Example: 1 person_values = list(person.values())

Sets

Package/Method	Description	Code Example
add()	Elements can be added to a set using the `add()` method. Duplicates are automatically removed, as sets only store unique values.	Syntax: 1 set_name.add(element) Example: 1 fruits.add("mango")
clear()	The `clear()` method removes all elements from the set, resulting in an empty set. It updates the set in-place.	Syntax: 1 set_name.clear() Example: 1 fruits.clear()
copy()	The `copy()` method creates a shallow copy of the set. Any modifications to the copy won't affect the original set.	Syntax: 1 new_set = set_name.copy() Example: 1 new_fruits = fruits.copy()
Defining Sets	A set is an unordered collection of unique elements. Sets are enclosed in curly braces `{}`. They are useful for storing distinct values and performing set operations.	Example: 1 2 empty_set = set() #Creating an Empty Set fruits = {"apple", "banana", "orange"}
discard()	Use the `discard()` method to remove a specific element from the set. Ignores if the element is not found.	Syntax: 1 set_name.discard(element) Example: 1 fruits.discard("apple")
issubset()	The `issubset()` method checks if the current set is a subset of another set. It returns True if all elements of the current set are present in the other set, otherwise False.	Syntax: 1 is_subset = set1.issubset(set2) Example: 1 is_subset = fruits.issubset(colors)
issuperset()	The `issuperset()` method checks if the current set is a superset of another set. It returns True if all elements of the other set are present in the current set, otherwise False.	Syntax: 1 is_superset = set1.issuperset(set2) Example: 1 is_superset = colors.issuperset(fruits)
pop()	The `pop()` method removes and returns an arbitrary element from the set. It raises a `KeyError` if the set is empty. Use this method to remove elements when the order doesn't matter.	Syntax: 1 removed_element = set_name.pop() Example: 1 removed_fruit = fruits.pop()
remove()	Use the `remove()` method to remove a specific element from the set. Raises a `KeyError` if the element is not found.	Syntax: 1 set_name.remove(element) Example: 1 fruits.remove("banana")
Set Operations	Perform various operations on sets: `union`, `intersection`, `difference`, `symmetric difference`.	Syntax: 1 2 3 4 union_set = set1.union(set2) intersection_set = set1.intersection(set2) difference_set = set1.difference(set2) sym_diff_set = set1.symmetric_difference(set2) Example: 1 2 3 4 combined = fruits.union(colors) common = fruits.intersection(colors) unique_to_fruits = fruits.difference(colors) sym_diff = fruits.symmetric_difference(colors)
update()	The `update()` method adds elements from another iterable into the set. It maintains the uniqueness of elements.	Syntax: 1 set_name.update(iterable) Example: 1 fruits.update(["kiwi", "grape"]