[PYTHON] Hamming code with numpy

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import numpy as np
import random

if __name__ == '__main__':
    k = 4
    m = 3

    #Create a list of non-powers of 2
    column_values = np.array([ [x] for x in range( 2 ** m ) if ( x & ( x - 1 ) ) != 0 ], dtype=np.uint8 )
    A = np.reshape( np.unpackbits( column_values ), ( k, 8) )[:, -3:].T

    #Create generator and check matrices
    H = np.concatenate( ( A, np.eye( m, dtype=np.uint8 ) ), axis=1 )
    G = np.concatenate( ( np.eye( k, dtype = np.uint8 ), A.T ), axis = 1 )

    #Appropriately set the value to be encoded
    random.seed()
    code = random.randint( 0, 2 ** k - 1 )
    bit_code = np.unpackbits( np.array( code, dtype = np.uint8 ) )[-k:]

    #Generate a Hamming code to invert a bit
    error_bit_offset = random.randint( 0, ( k + m ) - 1 )
    hamming_code = np.dot( bit_code, G ) % 2
    hamming_code[ error_bit_offset ] = ( hamming_code[ error_bit_offset ] + 1 ) % 2

    #Verification

    check_result = np.dot( H, hamming_code ) % 2

    print code
    print hamming_code
    print H
    print error_bit_offset
    print check_result

% ./hamming.py 
12
[1 0 0 0 1 1 0]
[[0 1 1 1 1 0 0]
 [1 0 1 1 0 1 0]
 [1 1 0 1 0 0 1]]
1
[1 0 1]

Recommended Posts