What Is {} Data Structure Python?


Scott Campbell

The {} data structure in Python is commonly referred to as a dictionary. It is an unordered collection of key-value pairs, where each key is unique and associated with its corresponding value. This data structure is incredibly versatile and widely used in Python programming.

Understanding Dictionaries

Dictionaries are created using curly braces ({}) and consist of comma-separated key-value pairs. The keys are typically strings, but they can also be other immutable data types such as numbers or tuples. The values, on the other hand, can be any data type – strings, numbers, lists, or even other dictionaries.

To access a value in a dictionary, you can use its corresponding key within square brackets ([]). For example:

my_dict = {'name': 'John', 'age': 25}
print(my_dict['name'])  # Output: John

Adding and Modifying Dictionary Elements

You can add new items to a dictionary by assigning a value to a new key:

my_dict['occupation'] = 'Engineer'

This will create a new key-value pair in the dictionary. If the specified key already exists, assigning a new value to it will update the existing value.

Dictionary Methods

Dictionaries come with various built-in methods that make it easier to work with them:

  • keys(): Returns all the keys in the dictionary.
  • values(): Returns all the values in the dictionary.
  • items(): Returns all the key-value pairs as tuples.
  • get(key): Returns the value associated with the specified key. If the key does not exist, it returns None or a default value specified as the second argument.
  • pop(key): Removes the key-value pair associated with the specified key and returns its value.

Iterating Over Dictionaries

You can loop over the keys, values, or items of a dictionary using a for loop:

my_dict = {'name': 'John', 'age': 25}
for key in my_dict:
    print(key)  # Output: name, age

for value in my_dict.values():
    print(value)  # Output: John, 25

for key, value in my_dict.items():
    print(key, value)  # Output: name John, age 25


The {} data structure in Python is a powerful tool for storing and organizing data. Its flexibility allows you to represent complex relationships between different entities. By understanding how to create, access, and manipulate dictionaries, you can take advantage of this data structure to write more efficient and elegant Python code.

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