checkdigit: Check Digit Library for Data Validation

0.5.0 · active · verified Thu Apr 09

checkdigit is a Python library providing algorithms for various check digit standards, facilitating data validation and error detection. It supports algorithms like Luhn, ISBN, UPC, EAN, ISIN, Modulo 10, Modulo 11, GS1, and CRC. The current version is 0.5.0, with releases occurring periodically to introduce new features, fix bugs, and refine existing algorithms.

Warnings

breaking The separate ISBN-10 and ISBN-13 validation/generation functions (e.g., `isbn10`, `isbn13`) were removed. All ISBN operations are now handled by a single `isbn` module.
Fix: Migrate usage from `checkdigit.formats.isbn10` or `checkdigit.formats.isbn13` to `checkdigit.isbn.validate()` or `checkdigit.isbn.generate()`. The unified `isbn` module automatically detects the ISBN type.
breaking Parity methods (e.g., `checkdigit.parity.missing()`) no longer return the full block of data. They now return only the calculated missing bit, aligning with the return behavior of other check digit methods.
Fix: Adjust code to expect only the missing bit as the return value from parity methods, rather than a full data structure.
breaking A significant refactoring in v0.1 led to many function renames to improve clarity and consistency. Code written for pre-0.1 versions will likely break.
Fix: Consult the official documentation or changelog for specific function name changes if migrating from versions prior to 0.1. It's generally recommended to upgrade and adapt to the current API.
gotcha Prior to v0.5.0, ISBN-13 validation incorrectly allowed 'X' as a check digit, which is only valid for ISBN-10. This could lead to incorrect validations for ISBN-13 codes.
Fix: Upgrade to checkdigit version 0.5.0 or newer to ensure correct ISBN-13 validation behavior.

Install

pip install checkdigit Install latest stable version

Imports

luhn
```
from checkdigit import luhn
```
Import specific algorithm modules (e.g., luhn, isbn, upc) directly from the top-level package.
isbn
```
from checkdigit import isbn
```
As of v0.3.0, dedicated isbn10 and isbn13 functions were removed. Use the unified `isbn` module.
gs1
```
from checkdigit import gs1
```

Quickstart

This quickstart demonstrates how to import and use the `luhn` and `isbn` modules to validate and generate check digits. The `isbn` module automatically handles both ISBN-10 and ISBN-13 formats.

from checkdigit import luhn
from checkdigit import isbn

# Validate a number using the Luhn algorithm
is_valid_luhn = luhn.validate("79927398713")
print(f"'79927398713' is valid Luhn: {is_valid_luhn}")

# Generate a check digit for a number
luhn_with_check = luhn.generate("7992739871")
print(f"'7992739871' with Luhn check digit: {luhn_with_check}")

# Validate an ISBN (supports both ISBN-10 and ISBN-13)
is_valid_isbn = isbn.validate("978-3-16-148410-0")
print(f"'978-3-16-148410-0' is valid ISBN: {is_valid_isbn}")

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