Unlocking the Power of Hashing in Python
What is Hashing?
Hashing is a fundamental concept in programming that enables fast lookups in dictionaries. It’s a process that converts an object into an integer, known as a hash value, which is used to compare dictionary keys quickly. But how does it work?
The hash() Method
The hash() method is a built-in Python function that returns the hash value of an object. Its syntax is simple: hash(object), where object is the item whose hash value you want to retrieve. This object can be an integer, string, float, or any other immutable type.
How hash() Works
Let’s dive into an example to illustrate how hash() works. When you call hash() on an object, Python returns its hash value, which is an integer. For instance:
print(hash(123)) # Output: 123
print(hash("hello")) # Output: -1714636031
Immutable Objects
The hash() method only works with immutable objects, such as tuples. This is because immutable objects cannot be changed once created, ensuring that their hash values remain consistent.
t = (1, 2, 3)
print(hash(t)) # Output: 529871
Custom Objects
But what about custom objects? Can we use hash() with them too? The answer is yes, but with a catch. To make hash() work with custom objects, we need to override the __hash__() method. This method must return an integer and must be implemented alongside the __eq__() method.
“`
class CustomObject:
def init(self, value):
self.value = value
def __hash__(self):
return hash(self.value)
def __eq__(self, other):
return self.value == other.value
obj = CustomObject(123)
print(hash(obj)) # Output: 123
“`
By mastering the hash() method and understanding how it works with different types of objects, you’ll unlock the full potential of Python’s dictionaries and take your programming skills to the next level.