use is_null_datetimelike instead

Author: Matt Roeschke

pandas/_libs/tslibs/nattype.pyx

@@ -39,18 +39,6 @@ _nat_scalar_rules[Py_GE] = False
 # ----------------------------------------------------------------------
 
 
-cpdef bint is_np_nat(x):
-    """Compat check for np.datetime('NaT')"""
-    try:
-        return np.isnat(x)
-    except AttributeError:
-        # numpy 1.12 compat
-        return str(x) == 'NaT'
-    except (TypeError, ValueError):
-        # np.isnat only defined for datetime, timedelta
-        return False
-
-
 def _make_nan_func(func_name, doc):
     def f(*args, **kwargs):
         return np.nan

pandas/io/formats/format.py

@@ -13,7 +13,7 @@
 from pandas._libs import lib
 from pandas._libs.tslib import format_array_from_datetime
 from pandas._libs.tslibs import NaT, Timedelta, Timestamp, iNaT
-from pandas._libs.tslibs.nattype import is_np_nat
+from pandas._libs.tslibs.nattype import is_null_datetimelike
 from pandas.compat import StringIO, lzip, map, u, zip
 
 from pandas.core.dtypes.common import (
@@ -947,7 +947,7 @@ def _format(x):
             if self.na_rep is not None and is_scalar(x) and isna(x):
                 if x is None:
                     return 'None'
-                elif x is NaT or is_np_nat(x):
+                elif x is NaT or is_null_datetimelike(x):
                     return 'NaT'
                 return self.na_rep
             elif isinstance(x, PandasObject):