How to iterate through alpha and numeric numbers

Question

I would like to know how in Python I can iterate through a set of conditions.

1. string that has 2-6 lower alpha or numeric characters
2. the first character is always a number

So a short progression would be:

1a
1b
1c
...
1aa
1ab
1ac
...
2aaa
2aab
2aac

etc.

A horrible example that can do the first two is

##Loop through 1a-z0-9
start = '1'
l = 97
while l < 123:
    num = start
    num += chr(l)
    print num
    l += 1

l = 48
while l < 58:
    num = start
    num += chr(l)
    print num
    l += 1

I found itertools but can't find good examples to go off of.

Answer 1

You can do this using itertools.product and itertools.chain. First define strings of the numbers and letters:

numbers = '0123456789'
alnum = numbers + 'abcdefghijklmnopqrstuvwxyz'

Using itertools.product, you can get tuples with the characters for the strings of various length:

len2 = itertools.product(numbers, alnum) # length 2
len3 = itertools.product(numbers, alnum, alnum) # length 3
...

Chain the iterators for all the lengths together, joining the tuples into strings. I'd do it with a list comprehension:

[''.join(p) for p in itertools.chain(len2, len3, len4, len5, len6)]

Answer 2

I would go with product function from itertools.

import itertools 
digits = '0123456789'
alphanum = 'abcdef...z' + digits # this should contain all the letters and digits

for i in xrange(1, 6):    
    for tok in itertools.product(digits, itertools.product(alphanum, repeat=i)):
        # do whatever you want with this token `tok` here.

Answer 3

You can think of this problem in base 26 (Ignoring the first number, we will put this in a separate case.) So with the letters we want to range from 'a' to 'zzzzz' in the base 26 would be 0 and (26,26,26,26,26) = 26 ^ 0 + 26 + 26^2 + 26^3 + 26^4 + 26^5. So now we have a bijection from numbers to letters, we just want to write a function that takes us from a number to a word

 letters = 'abcdef..z'

 def num_to_word( num ):
      res = ''
      while num:
           res += letters[num%26]
           num //= 26
      return res

Now to write our function that enumerates this

 def generator():
     for num in xrange(10):
         for letter_num in xrange( sum( 26 ** i for i in xrange( 6 ) ) + 1 ):
             tok = str(num) + num_to_word( letter_num )
             yield tok