Dictionary Data Structure In Python

Python, a versatile and powerful programming language, boasts a rich set of data structures that contribute to its popularity among developers. One such fundamental data structure is the dictionary. In this blog post, we'll explore the ins and outs of dictionaries in Python, understanding their methods.

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 {}.

dict_name = {} #Creates an empty dictionary 
person = { "name": "John", "age": 30, "city": "New York"}

Accessing Values

You can access the values in a dictionary using their corresponding keys.

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.

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.

person.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.

new_person = person.copy() 
new_person = dict(person) # another way to create a copy of dictionary

del

Removes the specified key-value pair from the dictionary. Raises a KeyError if the key does not exist.

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.

info = list(person.items())

In keyword

You can check for the existence of a key in a dictionary using the in keyword

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.

person_keys = list(person.keys())

Update()

The update() method merges the provided dictionary into the existing dictionary, adding or updating key-value pairs.

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.

person_values = list(person.values())