On 11/03/12 08:22, Roy Smith wrote: > Even better might be base-32 encoding the value. Strings of > digits have an information density of about 3.2 bits/char. > Base-32 is just about as readable, but gives you 5 bits/char, so > you end up with a few less characters (which you still want to > chunk into 3 or 4 character groups).
For things that will be read off a screen/paper, I recommend omitting several letters that are easy to mistake visually: i/I/l/1 and O/0 in particular. The VIN (vehicle identification number) on all US cars avoids these characters[*], making it easier to read them back without concern for "is that a zero or an oh; and is that an ell, a one, a lowercase eye, or a capital eye?" As an encoding advantage, >>> print len(''.join(c for c in (string.ascii_uppercase + string.digits) if c not in "O0iIl1")) 32 the number 32 is pretty handy when dealing with binary :-) -tkc [*] The VIN avoids "Q" too and does use the digits 0/1, but the idea holds. Make it easy to ready back. -- http://mail.python.org/mailman/listinfo/python-list