MNT: Deprecate date_ticker_factory (#23081)

oscargus · timhoffm · web-flow · commit 037fcca2066c · 2022-05-21T12:46:26.000+02:00
* Deprecate date_ticker_factory

* Update doc/api/next_api_changes/deprecations/23081-OG.rst

Co-authored-by: Tim Hoffmann &lt;2836374+timhoffm@users.noreply.github.com&gt;

Co-authored-by: Tim Hoffmann &lt;2836374+timhoffm@users.noreply.github.com&gt;
diff --git a/doc/api/next_api_changes/deprecations/23081-OG.rst b/doc/api/next_api_changes/deprecations/23081-OG.rst
@@ -0,0 +1,8 @@
+``date_ticker_factory`` deprecated
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``date_ticker_factory`` method in the `matplotlib.dates` module is
+deprecated. Instead use `~.AutoDateLocator` and `~.AutoDateFormatter` for a
+more flexible and scalable locator and formatter.
+
+If you need the exact ``date_ticker_factory`` behavior, please copy the code.
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -1782,6 +1782,8 @@ def num2epoch(d):
     return np.asarray(d) * SEC_PER_DAY - dt
 
 
+@_api.deprecated("3.6", alternative="`AutoDateLocator` and `AutoDateFormatter`"
+                 " or vendor the code")
 def date_ticker_factory(span, tz=None, numticks=5):
     """
     Create a date locator with *numticks* (approx) and a date formatter
diff --git a/lib/matplotlib/tests/test_dates.py b/lib/matplotlib/tests/test_dates.py
@@ -1319,8 +1319,9 @@ def test_concise_formatter_call():
                           (200, mdates.MonthLocator),
                           (2000, mdates.YearLocator)))
 def test_date_ticker_factory(span, expected_locator):
-    locator, _ = mdates.date_ticker_factory(span)
-    assert isinstance(locator, expected_locator)
+    with pytest.warns(_api.MatplotlibDeprecationWarning):
+        locator, _ = mdates.date_ticker_factory(span)
+        assert isinstance(locator, expected_locator)
 
 
 def test_usetex_newline():
