Python Access Dictionary

In Python, there are several ways to access values stored in a dictionary. Here’s a quick overview of the main methods:

Using Bracket Notation []

You can access dictionary values directly by referencing their keys within square brackets.

Note: This method will raise a KeyError if the key does not exist.

my_dict = {"name": "John", "age": 35, "city": "London"}
print(my_dict["name"])  # Output: John

Using the get() Method

The get() method allows safe access to values. If the key doesn’t exist, it returns None or a default value you specify.

This is a safer option if you’re unsure whether a key exists in the dictionary.

my_dict = {"name": "John", "age": 35}

# Access existing key
print(my_dict.get("age"))        # Output: 35

# Access non-existent key with default value
print(my_dict.get("salary", 0))  # Output: 0

Accessing All Keys, Values, and Key-Value Pairs

Keys: Use keys() to get all keys in the dictionary.

Values: Use values() to get all values in the dictionary.

Key-Value Pairs: Use items() to get all key-value pairs as tuples.

my_dict = {"name": "John", "age": 35, "city": "London"}

# Get all keys
print(my_dict.keys())    # Output: dict_keys(['name', 'age', 'city'])

# Get all values
print(my_dict.values())  # Output: dict_values(['John', 35, 'London'])

# Get all key-value pairs
print(my_dict.items())   # Output: dict_items([('name', 'John'), ('age', 35), ('city', 'London')])

Looping Through Dictionary Values

You can loop over a dictionary to access each key and value.

my_dict = {"name": "John", "age": 35, "city": "London"}

# Loop through keys
for key in my_dict:
    print(key, my_dict[key])

# Loop through values only
for value in my_dict.values():
    print(value)

# Loop through key-value pairs
for key, value in my_dict.items():
    print(f"{key}: {value}")

Using Default Dictionary with collections.defaultdict

defaultdict from the collections module automatically assigns a default value if a key doesn’t exist, so you don’t have to check manually.

from collections import defaultdict

my_dict = defaultdict(lambda: "Not Found")
my_dict["name"] = "John"

print(my_dict["name"])   # Output: John
print(my_dict["age"])    # Output: Not Found (default value)