Add datetime64 workaround for NumPy 1.10.

QuLogic · tacaswell · commit 08b5466622cc · 2018-02-13T08:57:20.000-05:00
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -283,7 +283,8 @@ def _dt64_to_ordinalf(d):
 
     # the "extra" ensures that we at least allow the dynamic range out to
     # seconds.  That should get out to +/-2e11 years.
-    extra = d - d.astype('datetime64[s]')
+    # NOTE: First cast truncates; second cast back is for NumPy 1.10.
+    extra = d - d.astype('datetime64[s]').astype(d.dtype)
     extra = extra.astype('timedelta64[ns]')
     t0 = np.datetime64('0001-01-01T00:00:00').astype('datetime64[s]')
     dt = (d.astype('datetime64[s]') - t0).astype(np.float64)
