Modernize indexes.timedeltas, indexes.datetimeindex (#18161)

(cherry picked from commit 079f678)

Author: jbrockmendel

pandas/core/indexes/datetimes.py

@@ -2,9 +2,11 @@
 from __future__ import division
 import operator
 import warnings
-from datetime import time, datetime
-from datetime import timedelta
+from datetime import time, datetime, timedelta
+
 import numpy as np
+from pytz import utc
+
 from pandas.core.base import _shared_docs
 
 from pandas.core.dtypes.common import (
@@ -55,18 +57,13 @@
 from pandas._libs.tslibs import timezones
 
 
-def _utc():
-    import pytz
-    return pytz.utc
-
 # -------- some conversion wrapper functions
 
 
 def _field_accessor(name, field, docstring=None):
     def f(self):
         values = self.asi8
         if self.tz is not None:
-            utc = _utc()
             if self.tz is not utc:
                 values = self._local_timestamps()
 
@@ -562,8 +559,6 @@ def _convert_for_op(self, value):
         raise ValueError('Passed item and index have different timezone')
 
     def _local_timestamps(self):
-        utc = _utc()
-
         if self.is_monotonic:
             return libts.tz_convert(self.asi8, utc, self.tz)
         else:
@@ -823,7 +818,6 @@ def _add_delta(self, delta):
 
         tz = 'UTC' if self.tz is not None else None
         result = DatetimeIndex(new_values, tz=tz, name=name, freq='infer')
-        utc = _utc()
         if self.tz is not None and self.tz is not utc:
             result = result.tz_convert(self.tz)
         return result
@@ -877,7 +871,6 @@ def astype(self, dtype, copy=True):
         raise ValueError('Cannot cast DatetimeIndex to dtype %s' % dtype)
 
     def _get_time_micros(self):
-        utc = _utc()
         values = self.asi8
         if self.tz is not None and self.tz is not utc:
             values = self._local_timestamps()

pandas/core/indexes/timedeltas.py

@@ -36,6 +36,26 @@
                           join as libjoin, Timedelta, NaT, iNaT)
 
 
+def _field_accessor(name, alias, docstring=None):
+    def f(self):
+        if self.hasnans:
+            result = np.empty(len(self), dtype='float64')
+            mask = self._isnan
+            imask = ~mask
+            result.flat[imask] = np.array([getattr(Timedelta(val), alias)
+                                           for val in self.asi8[imask]])
+            result[mask] = np.nan
+        else:
+            result = np.array([getattr(Timedelta(val), alias)
+                               for val in self.asi8], dtype='int64')
+
+        return Index(result, name=self.name)
+
+    f.__name__ = name
+    f.__doc__ = docstring
+    return property(f)
+
+
 def _td_index_cmp(opname, nat_result=False):
     """
     Wrap comparison operations to convert timedelta-like to timedelta64
@@ -380,46 +400,17 @@ def _format_native_types(self, na_rep=u('NaT'),
                                     nat_rep=na_rep,
                                     justify='all').get_result()
 
-    def _get_field(self, m):
-
-        values = self.asi8
-        hasnans = self.hasnans
-        if hasnans:
-            result = np.empty(len(self), dtype='float64')
-            mask = self._isnan
-            imask = ~mask
-            result.flat[imask] = np.array(
-                [getattr(Timedelta(val), m) for val in values[imask]])
-            result[mask] = np.nan
-        else:
-            result = np.array([getattr(Timedelta(val), m)
-                               for val in values], dtype='int64')
-        return Index(result, name=self.name)
-
-    @property
-    def days(self):
-        """ Number of days for each element. """
-        return self._get_field('days')
-
-    @property
-    def seconds(self):
-        """ Number of seconds (>= 0 and less than 1 day) for each element. """
-        return self._get_field('seconds')
-
-    @property
-    def microseconds(self):
-        """
-        Number of microseconds (>= 0 and less than 1 second) for each
-        element. """
-        return self._get_field('microseconds')
-
-    @property
-    def nanoseconds(self):
-        """
-        Number of nanoseconds (>= 0 and less than 1 microsecond) for each
-        element.
-        """
-        return self._get_field('nanoseconds')
+    days = _field_accessor("days", "days",
+                           " Number of days for each element. ")
+    seconds = _field_accessor("seconds", "seconds",
+                              " Number of seconds (>= 0 and less than 1 day) "
+                              "for each element. ")
+    microseconds = _field_accessor("microseconds", "microseconds",
+                                   "\nNumber of microseconds (>= 0 and less "
+                                   "than 1 second) for each\nelement. ")
+    nanoseconds = _field_accessor("nanoseconds", "nanoseconds",
+                                  "\nNumber of nanoseconds (>= 0 and less "
+                                  "than 1 microsecond) for each\nelement.\n")
 
     @property
     def components(self):