random.repy.md

random.repy

This module provides the programmer a randomizing utilize. This is almost an direct port of the python module, so one can certainly go to http://docs.python.org/library/random.html for more detailed information.

Functions

def random_randombytes(num_bytes, random_float=None):

Return a string of length num_bytes, made of random bytes suitable for cryptographic use (because randomfloat draws from a os provided random source).

Notes:

• num_bytes is the number of bytes to request from os.urandom. Must be a positive integer value.
• random_float does not work yet. Don't use.
• Returns a string of num_bytes random bytes suitable for cryptographic use.

def random_nbit_int(num_bits): 

Returns an random integer that was constructed with num_bits many random bits. The result will be an integer [0, 2**(num_bits) - 1] inclusive.

For Example: If a 10bit number is needed, random_nbit_int(10). Min should be greater or equal to 0. Max should be less than or equal to 1023.

Notes:

• num_bits is the number of random bits to be used for construction of the random integer to be returned.
• Raises TypeError if non-integer values for num_bits.
• Raises ValueError if the num_bits is negative or 0.
• Returns a random integer between [0, 2**(num_bits) - 1] inclusive.

def random_int_below(upper_bound):

Returns an random integer in the range [0,upper_bound)

Notes:

• The random integer returned will be greater than or equal to zero.
• The random integer returned will be less than the upper_bound.
• Handles the case where upper_bound has more bits than returned by a single call to the underlying generator.
• Raises TypeError if non-integer values for upper_bound.
• Raises ValueError if the upper_bound is negative or 0.

def random_randrange(start, stop=None, step=1):

Choose a random item from range(start, stop[, step]).

Notes:

• The random integer returned will be greater than or equal to start.
• The random integer returned will be less than stop.
• step determines which elements from the range will be considered.
• Raises ValueError if: Non-integer for start or stop argument, Empty range, if start < 0 and stop is None, Empty range, or Zero or non-integer step for range.

def random_randint(lower_bound, upper_bound):

Return random integer in range [lower_bound, upper_bound], including both end points.

Notes:

• The random integer returned will be less than or equal to the upper_bound.
• The random integer returned will be greater than or equal to the lower_bound.

def random_sample(population, k):

To return a list containing a random sample from the population.

Notes:

• population is the elements to be sampled from.
• k is the number of elements to sample.
• Raises ValueError is sampler larger than population.
• Returns a list of len(k) with random elements from the population.

Usage

random n bit example.

This will be a step by step walk through of the key operations
    defined in this function, with the largest possible
    10 bit integer returned.
    
    num_bits = 10
    
    randstring = random_randombytes(10/8)  for our example we
    will suppose that the byte returned was '
xff' (which is the
    same as chr(255)).
    
    odd_bits = 10 % 8 = 2
    Once again we assume that random_randombytes(1) returns the
    maximum possible, which is '
xff'  
    chr = ord('
xff') >> (8 - odd_bits)
    -> chr = 255 >> (8 - 2)
    -> chr = 255 >> 6 = 3   Note 3 is the largest 2 bit number
    chr(3) is appended to randstring resulting in
    randstring = '
x03
xff' 
    
    value = 0
    length = 2
    
    STEP 1 (i = 0):
      value = value << 8 
      -> value = 0
      value = value + ord(randstring[0])
      -> value = 3
    
    STEP 2 (i = 1):
      value = value << 8
      -> value = 768
      value = value + ord(randstring[1])
      -> value = 1023
    
    return 1023
    This is the maximum possible 10 bit integer.

Includes

[wiki:SeattleLib/math.repy]