Coding challenge for Symbiont

rander.py

#!/usr/bin/env python

import io
import os
import sys
import random
import atexit

fifo_path = "/tmp/rander.{0}".format(os.getpid())

def init(fifo_path):
	os.mkfifo(fifo_path)
	print "writing random bits to {0}".format(fifo_path)

def end(fifo_path):
	print "ending randomness"
	os.remove(fifo_path)

atexit.register(end, fifo_path)

def main(fifo_path):
	init(fifo_path)
	#write random bits endlessly to fifo
	while True:
		try: 
			fifo = io.open(fifo_path, "wb")
			while fifo.writable():
				fifo.write(chr(random.randrange(255)))
		except KeyboardInterrupt:
			break;
		except IOError:
			print "pipe broke, reopening..."
		except:
			print "Unexpected error:", sys.exc_info()[0]
			break;
	#atexit will clean up the fifo

main(fifo_path)

sample_random.py

#!/usr/bin/env python

import io

print "Loading randomness..."
path = "/tmp/rander.66733" # insert pipe here...
num_bytes = 100000000
bits_to_shift = 4
number_of_groups = 2 ** bits_to_shift

rand = io.open(path, "rb")
samples = [0] * number_of_groups
byte_values = rand.read(num_bytes)
ordinal_samples = [ord(c) >> bits_to_shift for c in byte_values]
for occurence in ordinal_samples:
	samples[occurence] += 1

print samples
maximum = max(samples)
minimum = min(samples)
mean = float(sum(samples)) / len(samples)
expected_mean = num_bytes / number_of_groups
print "Maximum:  {0} [{1}]".format(maximum, samples.index(maximum))
print "Minimum:  {0} [{1}]".format(minimum, samples.index(minimum))
print "Range:    {0}".format(maximum - minimum)
print "Expected: {0}".format(expected_mean)