This paper provides an introduction to the undate python
library with an emphasis on demonstrating supported functionality with
some example use cases from specific projects. undate is
designed for working with uncertain and partially known dates, and also
includes support for dates in multiple calendars and with mixed
precision. This paper provides an overview of the basic functionality
with comparison to the Python built-in datetime.date,
demonstrating support for missing and partially known values. Use cases
and data from Princeton Geniza Project and Shakespeare and
Company Project are used to further demonstrate the value and
practical application of undate for parsing and comparing
mixed precision dates in multiple calendars, and for calculating and
plotting durations for events with known days but unknown years.