From a9d4f4c692233c4c65e8b86e642ac74053cb16c3 Mon Sep 17 00:00:00 2001
From: Oscar Gustafsson <oscar.gustafsson@gmail.com>
Date: Thu, 21 Sep 2023 09:41:23 +0200
Subject: [PATCH] Remove Julian date support

---
 .../next_api_changes/removals/26852-OG.rst    |  5 ++
 lib/matplotlib/dates.py                       | 59 -------------------
 lib/matplotlib/tests/test_dates.py            | 17 ------
 3 files changed, 5 insertions(+), 76 deletions(-)
 create mode 100644 doc/api/next_api_changes/removals/26852-OG.rst

diff --git a/doc/api/next_api_changes/removals/26852-OG.rst b/doc/api/next_api_changes/removals/26852-OG.rst
new file mode 100644
index 000000000000..dc7d595f575f
--- /dev/null
+++ b/doc/api/next_api_changes/removals/26852-OG.rst
@@ -0,0 +1,5 @@
+``num2julian``, ``julian2num`` and ``JULIAN_OFFSET``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+... of the `.dates` module are removed without replacements. These were
+undocumented and not exported.
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
index a11e0d4f1ef6..c12d9f31ba4b 100644
--- a/lib/matplotlib/dates.py
+++ b/lib/matplotlib/dates.py
@@ -205,18 +205,6 @@
 UTC = datetime.timezone.utc
 
 
-@_api.caching_module_getattr
-class __getattr__:
-    JULIAN_OFFSET = _api.deprecated("3.7")(property(lambda self: 1721424.5))
-    # Julian date at 0000-12-31
-    # note that the Julian day epoch is achievable w/
-    # np.datetime64('-4713-11-24T12:00:00'); datetime64 is proleptic
-    # Gregorian and BC has a one-year offset.  So
-    # np.datetime64('0000-12-31') - np.datetime64('-4713-11-24T12:00') =
-    # 1721424.5
-    # Ref: https://en.wikipedia.org/wiki/Julian_day
-
-
 def _get_tzinfo(tz=None):
     """
     Generate `~datetime.tzinfo` from a string or return `~datetime.tzinfo`.
@@ -466,53 +454,6 @@ def date2num(d):
     return d if iterable else d[0]
 
 
-@_api.deprecated("3.7")
-def julian2num(j):
-    """
-    Convert a Julian date (or sequence) to a Matplotlib date (or sequence).
-
-    Parameters
-    ----------
-    j : float or sequence of floats
-        Julian dates (days relative to 4713 BC Jan 1, 12:00:00 Julian
-        calendar or 4714 BC Nov 24, 12:00:00, proleptic Gregorian calendar).
-
-    Returns
-    -------
-    float or sequence of floats
-        Matplotlib dates (days relative to `.get_epoch`).
-    """
-    ep = np.datetime64(get_epoch(), 'h').astype(float) / 24.
-    ep0 = np.datetime64('0000-12-31T00:00:00', 'h').astype(float) / 24.
-    # Julian offset defined above is relative to 0000-12-31, but we need
-    # relative to our current epoch:
-    dt = __getattr__("JULIAN_OFFSET") - ep0 + ep
-    return np.subtract(j, dt)  # Handles both scalar & nonscalar j.
-
-
-@_api.deprecated("3.7")
-def num2julian(n):
-    """
-    Convert a Matplotlib date (or sequence) to a Julian date (or sequence).
-
-    Parameters
-    ----------
-    n : float or sequence of floats
-        Matplotlib dates (days relative to `.get_epoch`).
-
-    Returns
-    -------
-    float or sequence of floats
-        Julian dates (days relative to 4713 BC Jan 1, 12:00:00).
-    """
-    ep = np.datetime64(get_epoch(), 'h').astype(float) / 24.
-    ep0 = np.datetime64('0000-12-31T00:00:00', 'h').astype(float) / 24.
-    # Julian offset defined above is relative to 0000-12-31, but we need
-    # relative to our current epoch:
-    dt = __getattr__("JULIAN_OFFSET") - ep0 + ep
-    return np.add(n, dt)  # Handles both scalar & nonscalar j.
-
-
 def num2date(x, tz=None):
     """
     Convert Matplotlib dates to `~datetime.datetime` objects.
diff --git a/lib/matplotlib/tests/test_dates.py b/lib/matplotlib/tests/test_dates.py
index 8995b9b35f09..4133524e0e1a 100644
--- a/lib/matplotlib/tests/test_dates.py
+++ b/lib/matplotlib/tests/test_dates.py
@@ -6,7 +6,6 @@
 import numpy as np
 import pytest
 
-import matplotlib as mpl
 from matplotlib import rc_context, style
 import matplotlib.dates as mdates
 import matplotlib.pyplot as plt
@@ -1282,22 +1281,6 @@ def test_change_interval_multiples():
     assert ax.get_xticklabels()[1].get_text() == 'Feb 01 2020'
 
 
-def test_julian2num():
-    mdates._reset_epoch_test_example()
-    mdates.set_epoch('0000-12-31')
-    with pytest.warns(mpl.MatplotlibDeprecationWarning):
-        # 2440587.5 is julian date for 1970-01-01T00:00:00
-        # https://en.wikipedia.org/wiki/Julian_day
-        assert mdates.julian2num(2440588.5) == 719164.0
-        assert mdates.num2julian(719165.0) == 2440589.5
-    # set back to the default
-    mdates._reset_epoch_test_example()
-    mdates.set_epoch('1970-01-01T00:00:00')
-    with pytest.warns(mpl.MatplotlibDeprecationWarning):
-        assert mdates.julian2num(2440588.5) == 1.0
-        assert mdates.num2julian(2.0) == 2440589.5
-
-
 def test_DateLocator():
     locator = mdates.DateLocator()
     # Test nonsingular