Pseudo random number & series generator, consistent across python 2.x and 3.x based on SHA

README.md

HELLO WORLD

a.txt

foo bar

crandom.py

import hashlib
seed_value = 1
i = 0 

def from_bytes (data):
    if isinstance(data, str):
        data = bytearray(data)
    num = 0
    for offset, byte in enumerate(data):
        num += byte << (offset * 8)
    return num

def seed(s):
    global seed_value, i
    i = 0
    if type(s) == int:
        s = str(s)
    seed_value = from_bytes(bytearray(s, 'UTF-8'))
    
def randint(a, b):
    '''Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b Generate random number between a <= N <=  b '''
    global i, seed_value
    k = str(seed_value+i).encode('utf-8')
    k = hashlib.sha224(k).hexdigest()
    k = int(k, 16)
    i+=1
    b+=1
    delta = b - a
    o = k % delta
    return int(a + o)

def serie(*s):
    '''Example of a series:
    
    serie(
        (1, (0, 1)),
        (2, (2, 4)),
    )
    Returns an array of 2 elements:
        First element is randomly chosen from [0, 1] with repetition.
        The next 3 elements are randomly chosen from [2,3,4] with repetition.
        
    Possible outputs:
        
        [0, 2, 2]
        [1, 4, 4]
        [0, 3, 4]
        ...
    '''
    o = []
    for part in s:
        for element in range(part[0]):
            o.append(randint(*part[1]))
    return o
        
def choice(options):
    return options[randint(0, len(options)-1)]

def verify():
    seed(124)
    assert(seed_value == 3420721)
    d = {0:0, 1:0, 2:0, 3:0}
    for j in range(1000):
        d[randint(0,3)]+=1
    if d[0] != 237:
        raise Exception("Consistency error! "+str(d[0])+' != 237')

if __name__ == '__main__':
    verify()

FOO

 11
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