86 lines
2.9 KiB
Python
86 lines
2.9 KiB
Python
# nhs.py - functions for handling United Kingdom NHS numbers
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#
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# Copyright (C) 2016-2017 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""NHS (United Kingdom National Health Service patient identifier).
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The NHS number is used by the NHS (National Health Service) and its partners
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to uniquely identify patients. The number is used in England, Wales and the
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Isle of Man. The number is assigned at birth and consists of 10 digits where
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the final digit is a check digit.
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More information:
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* https://en.wikipedia.org/wiki/NHS_number
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* https://www.nhs.uk/using-the-nhs/about-the-nhs/what-is-an-nhs-number/
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* https://digital.nhs.uk/article/301/NHS-Number
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* https://www.datadictionary.nhs.uk/data_dictionary/attributes/n/nhs/nhs_number_de.asp
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>>> validate('943-476-5870')
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'9434765870'
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>>> validate('9434765871') # invalid check digit
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> format('9434765870')
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'943 476 5870'
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"""
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from __future__ import annotations
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from stdnum.exceptions import *
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from stdnum.util import clean, isdigits
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def compact(number: str) -> str:
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"""Convert the number to the minimal representation. This strips the
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number of any valid separators and removes surrounding whitespace."""
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return clean(number, ' -').strip()
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def checksum(number: str) -> int:
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"""Calculate the checksum. The checksum is only used for the 9 digits
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of the number and the result can either be 0 or 42."""
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return sum(i * int(n) for i, n in enumerate(reversed(number), 1)) % 11
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def validate(number: str) -> str:
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"""Check if the number is valid. This checks the length and check
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digit."""
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number = compact(number)
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if not isdigits(number):
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raise InvalidFormat()
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if len(number) != 10:
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raise InvalidLength()
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if checksum(number) != 0:
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raise InvalidChecksum()
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return number
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def is_valid(number: str) -> bool:
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"""Check if the number is valid."""
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try:
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return bool(validate(number))
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except ValidationError:
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return False
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def format(number: str, separator: str = ' ') -> str:
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"""Reformat the number to the standard presentation format."""
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number = compact(number)
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return separator.join((number[0:3], number[3:6], number[6:]))
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