Am I programming in Python mode?
Martin von Loewis
loewis at informatik.hu-berlin.de
Wed Feb 2 17:27:41 EST 2000
Justin Sheehy <dworkin at ccs.neu.edu> writes:
> Note the error-checking in there. If you don't allow duplicates, you
> can't get a string longer than the set of allowed characters.
This gives the starting point to a different approach: If you don't
want duplicates, it is a matter of picking one element after another
from a set, and removing it after it was picked:
import string, random
def randStr(n, lower=1, duplicates=1):
chars = string.lowercase
chars = string.letters
chars = list(chars)
char_list = [None]*n
for i in range(0,n):
ch = random.choice(chars)
char_list[i] = ch
if not duplicates:
return string.join(char_list, '')
This also ignores the test for n>len(chars): You'll get an IndexError
if there are no chars left. It is faster if n is close to len(chars),
since it won't retry the same letters over and over again.
Also, since you'll know the length of the resulting string, you can
pre-allocate the list, and only fill the elements.
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