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@MrDHat
Created March 1, 2014 19:38
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Random Number Generator in Python
# imports for abstract classes
from abc import ABCMeta, abstractmethod
import time
''' ==============================================================================================
Seed Classes
==============================================================================================='''
class Seed(object):
"""Abstract class for seeds"""
__metaclass__ = ABCMeta
@abstractmethod
# Function that generates seed
def generate_seed(self):
pass
class TimeSeed(Seed):
""" Generates seed from current time """
def generate_seed(self):
return time.time()
''' ==============================================================================================
End Seed Classes
==============================================================================================='''
''' ==================================================================================================
Randomizer Classes
==================================================================================================='''
class Randomizer(object):
"""Abstract class to generate random numbers"""
__metaclass__ = ABCMeta
@abstractmethod
# Function that generates random numbers
# 'Decorate' seed onto the random number generator
def random(self, start, end, seed):
pass
class XORShiftRandomizer(Randomizer):
"""XOR Shift Randomizer"""
def random(self, start, end, seed):
random_number = seed.generate_seed()
# Get number after decimal point of seed because these are the numbers that actually vary
random_number = random_number % 1
random_number = str(random_number)
# Check if the number is decimal first
if random_number.find('.') != -1:
random_number = random_number.split('.')[1]
# Do not split if no decimal point and just take the integer as it is
random_number = int(random_number)
random_number ^= (random_number << 21);
random_number ^= (random_number >> 35);
random_number ^= (random_number << 4);
# Convert the generated number to lie between start and end
random_number = random_number % end
if random_number < start:
random_number = random_number + start
return random_number
''' ==================================================================================================
End Randomizer Classes
==================================================================================================='''
if __name__ == "__main__":
number_of_numbers = int(raw_input())
number_of_digits = int(raw_input())
xor_random = XORShiftRandomizer()
if number_of_numbers == 0:
exit(0)
# Calculate start and end of the range from number of digits
# start and end are starting as string because 0/9 will be appended to them and start and end will be generated. They will later be converted to integer
start = "1"
end = "9"
if number_of_digits == 0:
exit(0)
elif number_of_digits == 1:
start = 0
else:
while number_of_digits > 1:
start = start + "0"
end = end + "9"
number_of_digits = number_of_digits - 1
start = int(start)
end = int(end)
while number_of_numbers > 0:
print xor_random.random(start, end, TimeSeed())
number_of_numbers = number_of_numbers - 1
@MrDHat
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MrDHat commented Mar 12, 2014

lines 64, 65 and 66 are the lines that actually perform the randomisation operation. They are actually the core of randomisation function.
I've used XORShift randomisation technique which performs an "OR" operation between the number with its 'shifts'. The numbers 21, 35 and 4 are known to provide best possible results.

Note: This is not cryptographically secure but generates a true random number which can be used for generating random ID's etc.

@evbo
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evbo commented Oct 26, 2014

Just curious, what do you think about this article touting further speed improvements: http://xorshift.di.unimi.it/

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