|
Revision 7354, 0.7 kB
(checked in by jbronn, 8 months ago)
|
gis: Merged revisions 7280-7353 via svnmerge from trunk.
|
- Property svn:eol-style set to
native
|
| Line | |
|---|
| 1 |
""" |
|---|
| 2 |
Common checksum routines (used in multiple localflavor/ cases, for example). |
|---|
| 3 |
""" |
|---|
| 4 |
|
|---|
| 5 |
__all__ = ['luhn',] |
|---|
| 6 |
|
|---|
| 7 |
LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2) |
|---|
| 8 |
|
|---|
| 9 |
def luhn(candidate): |
|---|
| 10 |
""" |
|---|
| 11 |
Checks a candidate number for validity according to the Luhn |
|---|
| 12 |
algorithm (used in validation of, for example, credit cards). |
|---|
| 13 |
Both numeric and string candidates are accepted. |
|---|
| 14 |
""" |
|---|
| 15 |
if not isinstance(candidate, basestring): |
|---|
| 16 |
candidate = str(candidate) |
|---|
| 17 |
try: |
|---|
| 18 |
evens = sum([int(c) for c in candidate[-1::-2]]) |
|---|
| 19 |
odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]]) |
|---|
| 20 |
return ((evens + odds) % 10 == 0) |
|---|
| 21 |
except ValueError: # Raised if an int conversion fails |
|---|
| 22 |
return False |
|---|
