prettyisbns

A Python package for normalizing, fixing, and formatting ISBNs to make them pretty.

Installation

The package is available on PyPI:

pip install prettyisbns

Usage

Normalize and fix ISBNs

Normalize an ISBN and fix its check digit:

>>> from prettyisbns import normalize
>>> canonical = normalize("23-6590-117-X", fix=True)
>>> canonical
CanonicalISBN(9782365901178)

The result is a canonical, normalized ISBN-13 string without hyphens.

Format ISBNs

Format a canonical ISBN with hyphens to split it into elements:

>>> canonical.hyphenate()
'978-2-36590-117-8'

To normalize, fix, and format in one step, use the pretty() shortcut:

>>> from prettyisbns import pretty
>>> pretty("23-6590-117-X")
'978-2-36590-117-8'

Formatting relies on the registration groups and registrant ranges from the International ISBN Agency, which are stored in the auto-generated prettyisbns.ranges module. Ranges can be redefined, which may cause a discrepancy with the module. In that case, update the package or open an issue.

Access ISBN elements

Internally, formatting is done by ISBNLayout, which splits an ISBN into bookland, registration group, registrant, publication, and check digit elements. You can access it through the layout property, which supports slicing for a granular output:

# Split the canonical ISBN into its elements
>>> canonical.layout
ISBNLayout(
    bookland='978',
    group='2',
    registrant='36590',
    publication='117',
    check_digit='8',
)

# Get the group prefix
>>> canonical.layout[:2]
'978-2'

# Get the registrant prefix
>>> canonical.layout[:3]
'978-2-36590'

Validate ISBNs

Check an ISBN's check digit, registration group, and registrant range with validate(). It returns a ValidationResult, which is truthy only when the ISBN is valid:

if result := canonical.validate():
    print("valid")
else:
    print(f"invalid: {result.errors}")

Handle errors

Normalizing raises NotISBNError if a value is neither ISBN-10 nor ISBN-13, and formatting raises InvalidISBNError if the registration group or registrant range of an ISBN is not defined. Its reason attribute tells what exactly is wrong:

from prettyisbns import pretty
from prettyisbns.errors import InvalidISBNError, NotISBNError

try:
    prettied = pretty(value)
except NotISBNError:
    # The value is neither ISBN-10 nor ISBN-13
    ...
except InvalidISBNError as error:
    # The ISBN cannot be formatted, see error.reason
    ...

API

See the full API reference in the documentation.

License

MIT.