RosettaCodeData/Task/Validate-International-Securities-Identification-Number/Python/validate-international-securities-identification-number.py
2023-07-01 13:44:08 -04:00

33 lines
1 KiB
Python

def check_isin(a):
if len(a) != 12 or not all(c.isalpha() for c in a[:2]) or not all(c.isalnum() for c in a[2:]):
return False
s = "".join(str(int(c, 36)) for c in a)
return 0 == (sum(sum(divmod(2 * (ord(c) - 48), 10)) for c in s[-2::-2]) +
sum(ord(c) - 48 for c in s[::-2])) % 10
# A more readable version
def check_isin_alt(a):
if len(a) != 12:
return False
s = []
for i, c in enumerate(a):
if c.isdigit():
if i < 2:
return False
s.append(ord(c) - 48)
elif c.isupper():
if i == 11:
return False
s += divmod(ord(c) - 55, 10)
else:
return False
v = sum(s[::-2])
for k in s[-2::-2]:
k = 2 * k
v += k - 9 if k > 9 else k
return v % 10 == 0
[check_isin(s) for s in ["US0378331005", "US0373831005", "U50378331005", "US03378331005",
"AU0000XVGZA3", "AU0000VXGZA3", "FR0000988040"]]
# [True, False, False, False, True, True, True]