BUG: avoid a deprecation warning from numpy 2.5 (calling datetime64('NaT') without a unit is deprecated) (#31554)

neutrinoceros · timhoffm · web-flow · commit cf3aacfe162e · 2026-04-23T16:49:46.000-04:00
* BUG: avoid a deprecation warning from numpy 2.5 (calling `datetime64('NaT')` without a unit is deprecated)

Co-authored-by: Tim Hoffmann &lt;2836374+timhoffm@users.noreply.github.com&gt;
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -325,9 +325,7 @@ def _dt64_to_ordinalf(d):
     dt += extra.astype(np.float64) / 1.0e9
     dt = dt / SEC_PER_DAY
 
-    NaT_int = np.datetime64('NaT').astype(np.int64)
-    d_int = d.astype(np.int64)
-    dt[d_int == NaT_int] = np.nan
+    dt[np.isnat(d)] = np.nan
     return dt
 
 
