Python underlying technology revealed: how to implement hash algorithm

Revealing the underlying technology of Python: How to implement the hash algorithm, specific code examples are required

Abstract:
The hash algorithm is one of the commonly used technologies in the computer field , used to quickly determine the unique identifier of data. As a high-level language, Python provides many built-in hash functions, such as the hash() function and the implementation of various hash algorithms. This article will reveal the principles of hashing algorithms and the details of Python's underlying implementation, and provide specific code examples.

1. Introduction to Hash Algorithm
   Hash algorithm, also known as hash algorithm, is an algorithm that converts input data of any length into a fixed-length output. This output is the hash value, also known as the hash code or digest. The hash algorithm has the characteristics of fast calculation, fixed length and data irreversibility. Common hashing algorithms include MD5, SHA-1, SHA-256, etc.
2. Python built-in hash function
   Python provides the built-in hash function hash(), which can perform hash calculations on immutable type data. The specific usage is as follows:

# 使用hash()函数计算哈希值
data = "Hello, World!"
hash_value = hash(data)
print(hash_value)

3. Implementation principle of hash algorithm
   The implementation principle of hash algorithm is divided into two steps: compression and perturbation. Compression maps raw data into a smaller space, converting arbitrary-length input into fixed-length output. Perturbation is a series of bit operations and arithmetic operations that allow subtle changes in input data to cause huge changes in the output hash value.
4. Implementing a simple hash algorithm
   The following is an implementation example of a simple hash algorithm, which converts a string into a 32-bit hash value:

def simple_hash(data):
    hash_value = 0
    for character in data:
        hash_value = (hash_value * 31 + ord(character)) & 0xFFFFFFFF
    return hash_value

data = "Hello, World!"
hash_value = simple_hash(data)
print(hash_value)

5. Implementation of Python's underlying hash algorithm
   The bottom layer of Python uses a fast, non-encrypted hash function called "MurmurHash". It maps input data to a 32-bit hash value through a series of bit operations and arithmetic operations. The MurmurHash algorithm is implemented as a C language extension module in Python, which improves calculation speed.
6. Hash collisions in Python
   Since hashing algorithms map inputs of arbitrary length to outputs of fixed length, different inputs may produce the same hash value, that is, hash collisions. In order to solve hash conflicts, Python uses a solution called "open addressing" under the hood. When a hash collision occurs, Python tries to store the data in the next available location in the hash table until a free location is found.

Conclusion:
The hash algorithm is a commonly used technology to quickly determine the unique identification of data. Python provides a built-in hash() function and a fast implementation of the underlying hash algorithm. Understanding the principles of hashing algorithms and the underlying implementation details of Python is of great significance for writing efficient programs and optimizing algorithms. Through the explanation and code examples of this article, I hope readers can master the basic principles and implementation methods of hash algorithms, and be able to flexibly apply them in actual development.

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