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The many uses of randomness - Part 2 (Python recipe) by Vasudev Ram
ActiveState Code (http://code.activestate.com/recipes/580690/)

This is the second recipe in the series about the uses of randomness in Python. The first recipe is here:

https://code.activestate.com/recipes/580674-the-many-uses-of-randomness-part-1/?in=user-4173351

This second recipe shows some uses of random numbers to generate random characters and random strings of various categories, and some purposes for which these generated strings can be used in testing.

Python, 80 lines
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# Setup code.

from __future__ import print_function
import string
from random import random, randint, randrange, choice, shuffle

'''
1) Random characters from the range of 7-bit ASCII characters, i.e. the characters with ASCII codes 0 to 127. This expression generates a single ASCII character:
'''
chr(randint(0, 127))

'''
To generate only printable ASCII characters, use:
'''
choice(string.printable)

'''
Generate random uppercase letter.
'''
chr(randint(ord('A'), ord('Z')))

'''
Or, another way:
Generate random uppercase letter.
'''
choice(string.ascii_uppercase)

'''
Generate random lowercase letter.
'''
chr(randint(ord('a'), ord('z')))

'''
Or, another way:
Generate random lowercase letter.
'''
choice(string.ascii_lowercase)

'''
Generate strings with random character content but fixed length, e.g.: "tdczs", "ohybi", "qhmyf", "elazk"
'''
def rand_lcase_str(n):
    '''Return string of n random lowercase letters.'''
    assert n > 0
    rand_chars = [ choice(string.ascii_lowercase) for i in range(n) ]
    return ''.join(rand_chars)

[ rand_lcase_str(3) for i in range(1, 8) ]
# Output:
# ['xio', 'qsc', 'omt', 'fnn', 'ezz', 'get', 'frs']

[ rand_lcase_str(7) for i in range(1, 4) ]
# Output:
# ['hazrdwu', 'sfvvxno', 'djmhxri']

'''
Generate strings with fixed character content but random lengths, e.g.: "g", "gggg", "gg", "ggggg", "ggg"; all strings contain only letter g's, but are of different lengths.
'''
def rand_len_fixed_char_str(c, low_len=1, high_len=256):
    '''Return a string containing a number of characters c,
    varying randomly in length between low_len and high_len'''
    assert len(c) == 1
    assert 0 < low_len <= high_len
    rand_chars = c * randint(low_len, high_len)
    return rand_chars

[ rand_len_fixed_char_str('g', 3, 8) for i in range(10) ]
# Output:
'''
['gggg',
 'ggggggg',
 'ggg',
 'ggggggg',
 'ggggg',
 'ggggg',
 'gggggg',
 'gggggg',
 'gggggg',
 'ggggg']
'''
Tags: random, random_number, simulation, testing