Python Dictionary Operations

Data in a dictionary appears in key-value pairs and does not support indexing.

1 – Adding Data to a Dictionary

Syntax: dictionary[key] = value

If the key exists, modify the value of the key; if it does not exist, add this key-value pair.

dict1 = {"name": "Xiaomi", "age": 18}dict1["sex"] = "male"print(dict1)    #{'name': 'Xiaomi', 'age': 18, 'sex': 'male'}dict1["sex"] = "female"print(dict1)    #{'name': 'Xiaomi', 'age': 18, 'sex': 'female'}

2 – Deleting Data from a Dictionary

Syntax:

del(): Deletes the dictionary or deletes the specified key-value pair from the dictionary.

clear(): Clears the dictionary.

dict1 = {"name": "Xiaomi", "age": 18}del dict1["age"]print(dict1)    #{'name': 'Xiaomi'}dict1.clear()print(dict1)    #{}

3 – Searching in a Dictionary

1) Key lookup: If the key exists, return the corresponding value; otherwise, raise an error.

2) Function lookup

get(): If the key being searched does not exist, return the second parameter; if the second parameter is omitted, return None.

Syntax: dictionary.get(key, default_value)

keys()

values()

items()

dict1 = {"name": "Xiaomi", "age": 18}print(dict1["name"])    # Xiaomi#print(dict1["sex"])     # Errorprint(dict1.get("age")) # 18print(dict1.get("sex")) # Noneprint(dict1.keys()) # dict_keys(['name', 'age'])print(dict1.values())   # dict_values(['Xiaomi', 18])print(dict1.items()) # dict_items([('name', 'Xiaomi'), ('age', 18)])

4 – Iterating Over Dictionary KeysGet the key elements in the dictionary.

dict1 = {"name": "Xiaomi", "age": 18, "sex": "male"}for key in dict1.keys():        print(key)  # name age sex

5 – Iterating Over Dictionary Values

dict1 = {"name": "Xiaomi", "age": 18, "sex": "male"}for value in dict1.values():        print(value)    # Xiaomi 18 male

6 – Getting Key-Value Pairs

Returns an iterable object, where each item is a tuple containing two elements: the key and the value of the dictionary.

dict1 = {"name": "Xiaomi", "age": 18, "sex": "male"}for item in dict1.items():        # Returns an iterable object, where each item is a tuple containing two elements: the key and the value of the dictionary.        print(item)    # ('name', 'Xiaomi')  ('age', 18) ('sex', 'male')

7 – Unpacking Key-Value Pairs

dict1 = {"name": "Xiaomi", "age": 18, "sex": "male"}for key, value in dict1.items():        # Returns an iterable object, where each item is a tuple containing two elements: the key and the value of the dictionary.        print(key)        print(value)        print(f"{key}={value}")