Python are a widely used data structure that stores a collection of - pairs. Each key in a dictionary must be unique, and it is associated with a specific value. The key provides a way to access the corresponding value quickly, making dictionaries an efficient data structure when retrieving specific information.
Dictionaries are , meaning that their can be modified once they are created. However, the key of a dictionary is and cannot be changed. This property allows for easy updating of values by providing the key and assigning a new value to it.
The of a dictionary can be determined using the len() function, which returns the number of key-value pairs present in the dictionary. To a dictionary, we can use the update() method, which takes another dictionary or an iterable of key-value pairs as input and adds them to the existing dictionary.
The () method can be used to obtain a list of all the keys present in a dictionary, while the values() method returns a list of all the values. To remove all the from a dictionary, the () method can be used. Alternatively, the () method allows for the removal of a specific item, identified by its key.
can also be created in Python, allowing for the organization of data in a hierarchical manner. This is achieved by having dictionaries as the values of other dictionaries, forming a structure where each key corresponds to another dictionary.
Under the hood, dictionaries in Python use a implementation to efficiently store and retrieve key-value pairs. This hash table is a data structure that maps keys to specific locations within the dictionary.
Python provides several to manipulate and access dictionary contents. The items() method returns a list of all key-value pairs as tuples, while the () method allows for the retrieval of a value based on its key. The setdefault() method is used to both get the value for a specific key and set a default value if the key is not found.
The "in" operator can be utilized to check whether a specific key is present in a dictionary. It returns True if the key exists, and False otherwise. To create a of a dictionary, the copy() method can be used, which returns a shallow copy of the original dictionary.
Additionally, is a concise way to create dictionaries in Python. It allows for the creation of dictionaries by specifying a key-value pair along with an iterable and a condition if desired, all within a single line of code. This powerful feature provides a compact syntax for creating dictionaries based on existing data.
