CLN: Period cleanup related to array like meth

removed unused / duplicated internal method
returning array-likes. Also added some tests to guarantee existing API
before fixing its dtype (see #13941).

Author: sinhrks <[email protected]>

Closes #13955 from sinhrks/object_array_cln and squashes the following commits:

a75a718 [sinhrks] CLN: Period cleanup related to array like meth

Author: sinhrks

pandas/tseries/period.py

@@ -402,9 +402,6 @@ def asof_locs(self, where, mask):
 
         return result
 
-    def _array_values(self):
-        return self.asobject
-
     @Appender(_index_shared_docs['astype'])
     def astype(self, dtype, copy=True):
         dtype = np.dtype(dtype)
@@ -541,14 +538,9 @@ def start_time(self):
     def end_time(self):
         return self.to_timestamp(how='end')
 
-    def _get_object_array(self):
-        freq = self.freq
-        return np.array([Period._from_ordinal(ordinal=x, freq=freq)
-                         for x in self.values], copy=False)
-
     def _mpl_repr(self):
         # how to represent ourselves to matplotlib
-        return self._get_object_array()
+        return self.asobject.values
 
     def equals(self, other):
         """

pandas/tseries/tests/test_period.py

@@ -1783,24 +1783,6 @@ def test_constructor_datetime64arr(self):
 
         self.assertRaises(ValueError, PeriodIndex, vals, freq='D')
 
-    def test_view(self):
-        idx = pd.PeriodIndex([], freq='M')
-
-        exp = np.array([], dtype=np.int64)
-        tm.assert_numpy_array_equal(idx.view('i8'), exp)
-        tm.assert_numpy_array_equal(idx.asi8, exp)
-
-        idx = pd.PeriodIndex(['2011-01', pd.NaT], freq='M')
-
-        exp = np.array([492, -9223372036854775808], dtype=np.int64)
-        tm.assert_numpy_array_equal(idx.view('i8'), exp)
-        tm.assert_numpy_array_equal(idx.asi8, exp)
-
-        exp = np.array([14975, -9223372036854775808], dtype=np.int64)
-        idx = pd.PeriodIndex(['2011-01-01', pd.NaT], freq='D')
-        tm.assert_numpy_array_equal(idx.view('i8'), exp)
-        tm.assert_numpy_array_equal(idx.asi8, exp)
-
     def test_constructor_empty(self):
         idx = pd.PeriodIndex([], freq='M')
         tm.assertIsInstance(idx, PeriodIndex)
@@ -1988,6 +1970,66 @@ def test_constructor_freq_combined(self):
                                    freq='25H')
             tm.assert_index_equal(pidx, expected)
 
+    def test_view_asi8(self):
+        idx = pd.PeriodIndex([], freq='M')
+
+        exp = np.array([], dtype=np.int64)
+        tm.assert_numpy_array_equal(idx.view('i8'), exp)
+        tm.assert_numpy_array_equal(idx.asi8, exp)
+
+        idx = pd.PeriodIndex(['2011-01', pd.NaT], freq='M')
+
+        exp = np.array([492, -9223372036854775808], dtype=np.int64)
+        tm.assert_numpy_array_equal(idx.view('i8'), exp)
+        tm.assert_numpy_array_equal(idx.asi8, exp)
+
+        exp = np.array([14975, -9223372036854775808], dtype=np.int64)
+        idx = pd.PeriodIndex(['2011-01-01', pd.NaT], freq='D')
+        tm.assert_numpy_array_equal(idx.view('i8'), exp)
+        tm.assert_numpy_array_equal(idx.asi8, exp)
+
+    def test_values(self):
+        # ToDo: .values and .get_values() should return Period as object
+        # dtype array. ._values shouldn't be changed
+        idx = pd.PeriodIndex([], freq='M')
+
+        exp = np.array([], dtype=np.int64)
+        tm.assert_numpy_array_equal(idx.values, exp)
+        tm.assert_numpy_array_equal(idx.get_values(), exp)
+        tm.assert_numpy_array_equal(idx._values, exp)
+
+        idx = pd.PeriodIndex(['2011-01', pd.NaT], freq='M')
+
+        exp = np.array([492, -9223372036854775808], dtype=np.int64)
+        tm.assert_numpy_array_equal(idx.values, exp)
+        tm.assert_numpy_array_equal(idx.get_values(), exp)
+        tm.assert_numpy_array_equal(idx._values, exp)
+
+        exp = np.array([14975, -9223372036854775808], dtype=np.int64)
+        idx = pd.PeriodIndex(['2011-01-01', pd.NaT], freq='D')
+        tm.assert_numpy_array_equal(idx.values, exp)
+        tm.assert_numpy_array_equal(idx.get_values(), exp)
+        tm.assert_numpy_array_equal(idx._values, exp)
+
+    def test_asobject_like(self):
+        idx = pd.PeriodIndex([], freq='M')
+
+        exp = np.array([], dtype=object)
+        tm.assert_numpy_array_equal(idx.asobject.values, exp)
+        tm.assert_numpy_array_equal(idx._mpl_repr(), exp)
+
+        idx = pd.PeriodIndex(['2011-01', pd.NaT], freq='M')
+
+        exp = np.array([pd.Period('2011-01', freq='M'), pd.NaT], dtype=object)
+        tm.assert_numpy_array_equal(idx.asobject.values, exp)
+        tm.assert_numpy_array_equal(idx._mpl_repr(), exp)
+
+        exp = np.array([pd.Period('2011-01-01', freq='D'), pd.NaT],
+                       dtype=object)
+        idx = pd.PeriodIndex(['2011-01-01', pd.NaT], freq='D')
+        tm.assert_numpy_array_equal(idx.asobject.values, exp)
+        tm.assert_numpy_array_equal(idx._mpl_repr(), exp)
+
     def test_is_(self):
         create_index = lambda: PeriodIndex(freq='A', start='1/1/2001',
                                            end='12/1/2009')