PR summary

This PR intends to close [ENH]: Support using datetimes as positions argument to violin(...)#30417

It should be possible to set the position of a violin plot to be a datetime. Currently, an attempt to do this results in this error message:TypeError: unsupported operand type(s) for +: 'float' and 'datetime.datetime'

The error stems from trying to perform operations between float and datetime if datetime was provided as position arguments.

The proposed solution:

• Converts datetimes in the "position" argument of a violin plot to float representation using date2num function in matplotlib.dates.
• Converts any "width" argument in the form of time difference to days.

The violinplot tests in test_axes.py were successful

An example that tests both "width" and "positions":

Example:

import datetimeimport matplotlib.pyplot as pltfig, ax = plt.subplots()datetimes = [    datetime.datetime(2023, 2, 10),    datetime.datetime(2023, 5, 18),    datetime.datetime(2023, 6, 6)]ax.violin(    [        {            'coords': datetimes,            'vals': [0.1, 0.5, 0.2],            'mean': datetimes[1],            'median': datetimes[1],            'min': datetimes[0],            'max': datetimes[-1],            'quantiles': datetimes        }    ],    positions=[datetime.datetime(2023, 1, 1)],    widths=[datetime.timedelta(days=1)])

PR checklist

• "closes[ENH]: Support using datetimes aspositions argument to violin(...) #30417" is in the body of the PR description tolink the related issue
• new and changed code istested
• Plotting related features are demonstrated in anexample
• New Features andAPI Changes are noted with adirective and release note
• Documentation complies withgeneral anddocstring guidelines