CLN: remove BlockManager.get (pandas-dev#33052)

* CLN: remove BlockManager.get

* Remove assertions

Author: jbrockmendel

pandas/core/frame.py

@@ -2586,7 +2586,7 @@ def _ixs(self, i: int, axis: int = 0):
             label = self.columns[i]
 
             values = self._mgr.iget(i)
-            result = self._box_col_values(values, label)
+            result = self._box_col_values(values, i)
 
             # this is a cached value, mark it so
             result._set_as_cached(label, self)
@@ -2691,7 +2691,7 @@ def _getitem_bool_array(self, key):
     def _getitem_multilevel(self, key):
         # self.columns is a MultiIndex
         loc = self.columns.get_loc(key)
-        if isinstance(loc, (slice, Series, np.ndarray, Index)):
+        if isinstance(loc, (slice, np.ndarray)):
             new_columns = self.columns[loc]
             result_columns = maybe_droplevels(new_columns, key)
             if self._is_mixed_type:
@@ -2724,7 +2724,8 @@ def _getitem_multilevel(self, key):
             result._set_is_copy(self)
             return result
         else:
-            return self._get_item_cache(key)
+            # loc is neither a slice nor ndarray, so must be an int
+            return self._ixs(loc, axis=1)
 
     def _get_value(self, index, col, takeable: bool = False):
         """
@@ -2915,19 +2916,15 @@ def _ensure_valid_index(self, value):
                 value.index.copy(), axis=1, fill_value=np.nan
             )
 
-    def _box_item_values(self, key, values):
-        items = self.columns[self.columns.get_loc(key)]
-        if values.ndim == 2:
-            return self._constructor(values.T, columns=items, index=self.index)
-        else:
-            return self._box_col_values(values, items)
-
-    def _box_col_values(self, values, items):
+    def _box_col_values(self, values, loc: int) -> Series:
         """
         Provide boxed values for a column.
         """
+        # Lookup in columns so that if e.g. a str datetime was passed
+        #  we attach the Timestamp object as the name.
+        name = self.columns[loc]
         klass = self._constructor_sliced
-        return klass(values, index=self.index, name=items, fastpath=True)
+        return klass(values, index=self.index, name=name, fastpath=True)
 
     # ----------------------------------------------------------------------
     # Unsorted

pandas/core/generic.py

@@ -3558,18 +3558,20 @@ def _get_item_cache(self, item):
         cache = self._item_cache
         res = cache.get(item)
         if res is None:
-            values = self._mgr.get(item)
-            res = self._box_item_values(item, values)
+            # All places that call _get_item_cache have unique columns,
+            #  pending resolution of GH#33047
+
+            loc = self.columns.get_loc(item)
+            values = self._mgr.iget(loc)
+            res = self._box_col_values(values, loc)
+
             cache[item] = res
             res._set_as_cached(item, self)
 
             # for a chain
             res._is_copy = self._is_copy
         return res
 
-    def _box_item_values(self, key, values):
-        raise AbstractMethodError(self)
-
     def _slice(self: FrameOrSeries, slobj: slice, axis=0) -> FrameOrSeries:
         """
         Construct a slice of this container.

pandas/core/internals/managers.py

@@ -935,35 +935,6 @@ def _consolidate_inplace(self) -> None:
             self._known_consolidated = True
             self._rebuild_blknos_and_blklocs()
 
-    def get(self, item):
-        """
-        Return values for selected item (ndarray or BlockManager).
-        """
-        if self.items.is_unique:
-
-            if not isna(item):
-                loc = self.items.get_loc(item)
-            else:
-                indexer = np.arange(len(self.items))[isna(self.items)]
-
-                # allow a single nan location indexer
-                if not is_scalar(indexer):
-                    if len(indexer) == 1:
-                        loc = indexer.item()
-                    else:
-                        raise ValueError("cannot label index with a null key")
-
-            return self.iget(loc)
-        else:
-
-            if isna(item):
-                raise TypeError("cannot label index with a null key")
-
-            indexer = self.items.get_indexer_for([item])
-            return self.reindex_indexer(
-                new_axis=self.items[indexer], indexer=indexer, axis=0, allow_dups=True
-            )
-
     def iget(self, i: int) -> "SingleBlockManager":
         """
         Return the data as a SingleBlockManager.

pandas/tests/internals/test_internals.py

@@ -329,45 +329,48 @@ def test_categorical_block_pickle(self):
         smgr2 = tm.round_trip_pickle(smgr)
         tm.assert_series_equal(Series(smgr), Series(smgr2))
 
-    def test_get(self):
+    def test_iget(self):
         cols = Index(list("abc"))
         values = np.random.rand(3, 3)
         block = make_block(values=values.copy(), placement=np.arange(3))
         mgr = BlockManager(blocks=[block], axes=[cols, np.arange(3)])
 
-        tm.assert_almost_equal(mgr.get("a").internal_values(), values[0])
-        tm.assert_almost_equal(mgr.get("b").internal_values(), values[1])
-        tm.assert_almost_equal(mgr.get("c").internal_values(), values[2])
+        tm.assert_almost_equal(mgr.iget(0).internal_values(), values[0])
+        tm.assert_almost_equal(mgr.iget(1).internal_values(), values[1])
+        tm.assert_almost_equal(mgr.iget(2).internal_values(), values[2])
 
     def test_set(self):
         mgr = create_mgr("a,b,c: int", item_shape=(3,))
 
         mgr.set("d", np.array(["foo"] * 3))
         mgr.set("b", np.array(["bar"] * 3))
-        tm.assert_numpy_array_equal(mgr.get("a").internal_values(), np.array([0] * 3))
+        tm.assert_numpy_array_equal(mgr.iget(0).internal_values(), np.array([0] * 3))
         tm.assert_numpy_array_equal(
-            mgr.get("b").internal_values(), np.array(["bar"] * 3, dtype=np.object_)
+            mgr.iget(1).internal_values(), np.array(["bar"] * 3, dtype=np.object_)
         )
-        tm.assert_numpy_array_equal(mgr.get("c").internal_values(), np.array([2] * 3))
+        tm.assert_numpy_array_equal(mgr.iget(2).internal_values(), np.array([2] * 3))
         tm.assert_numpy_array_equal(
-            mgr.get("d").internal_values(), np.array(["foo"] * 3, dtype=np.object_)
+            mgr.iget(3).internal_values(), np.array(["foo"] * 3, dtype=np.object_)
         )
 
     def test_set_change_dtype(self, mgr):
         mgr.set("baz", np.zeros(N, dtype=bool))
 
         mgr.set("baz", np.repeat("foo", N))
-        assert mgr.get("baz").dtype == np.object_
+        idx = mgr.items.get_loc("baz")
+        assert mgr.iget(idx).dtype == np.object_
 
         mgr2 = mgr.consolidate()
         mgr2.set("baz", np.repeat("foo", N))
-        assert mgr2.get("baz").dtype == np.object_
+        idx = mgr2.items.get_loc("baz")
+        assert mgr2.iget(idx).dtype == np.object_
 
         mgr2.set("quux", tm.randn(N).astype(int))
-        assert mgr2.get("quux").dtype == np.int_
+        idx = mgr2.items.get_loc("quux")
+        assert mgr2.iget(idx).dtype == np.int_
 
         mgr2.set("quux", tm.randn(N))
-        assert mgr2.get("quux").dtype == np.float_
+        assert mgr2.iget(idx).dtype == np.float_
 
     def test_copy(self, mgr):
         cp = mgr.copy(deep=False)
@@ -430,8 +433,8 @@ def test_as_array_datetime(self):
 
     def test_as_array_datetime_tz(self):
         mgr = create_mgr("h: M8[ns, US/Eastern]; g: M8[ns, CET]")
-        assert mgr.get("h").dtype == "datetime64[ns, US/Eastern]"
-        assert mgr.get("g").dtype == "datetime64[ns, CET]"
+        assert mgr.iget(0).dtype == "datetime64[ns, US/Eastern]"
+        assert mgr.iget(1).dtype == "datetime64[ns, CET]"
         assert mgr.as_array().dtype == "object"
 
     @pytest.mark.parametrize("t", ["float16", "float32", "float64", "int32", "int64"])
@@ -441,26 +444,26 @@ def test_astype(self, t):
 
         t = np.dtype(t)
         tmgr = mgr.astype(t)
-        assert tmgr.get("c").dtype.type == t
-        assert tmgr.get("d").dtype.type == t
-        assert tmgr.get("e").dtype.type == t
+        assert tmgr.iget(0).dtype.type == t
+        assert tmgr.iget(1).dtype.type == t
+        assert tmgr.iget(2).dtype.type == t
 
         # mixed
         mgr = create_mgr("a,b: object; c: bool; d: datetime; e: f4; f: f2; g: f8")
 
         t = np.dtype(t)
         tmgr = mgr.astype(t, errors="ignore")
-        assert tmgr.get("c").dtype.type == t
-        assert tmgr.get("e").dtype.type == t
-        assert tmgr.get("f").dtype.type == t
-        assert tmgr.get("g").dtype.type == t
+        assert tmgr.iget(2).dtype.type == t
+        assert tmgr.iget(4).dtype.type == t
+        assert tmgr.iget(5).dtype.type == t
+        assert tmgr.iget(6).dtype.type == t
 
-        assert tmgr.get("a").dtype.type == np.object_
-        assert tmgr.get("b").dtype.type == np.object_
+        assert tmgr.iget(0).dtype.type == np.object_
+        assert tmgr.iget(1).dtype.type == np.object_
         if t != np.int64:
-            assert tmgr.get("d").dtype.type == np.datetime64
+            assert tmgr.iget(3).dtype.type == np.datetime64
         else:
-            assert tmgr.get("d").dtype.type == t
+            assert tmgr.iget(3).dtype.type == t
 
     def test_convert(self):
         def _compare(old_mgr, new_mgr):
@@ -497,11 +500,11 @@ def _compare(old_mgr, new_mgr):
         mgr.set("b", np.array(["2."] * N, dtype=np.object_))
         mgr.set("foo", np.array(["foo."] * N, dtype=np.object_))
         new_mgr = mgr.convert(numeric=True)
-        assert new_mgr.get("a").dtype == np.int64
-        assert new_mgr.get("b").dtype == np.float64
-        assert new_mgr.get("foo").dtype == np.object_
-        assert new_mgr.get("f").dtype == np.int64
-        assert new_mgr.get("g").dtype == np.float64
+        assert new_mgr.iget(0).dtype == np.int64
+        assert new_mgr.iget(1).dtype == np.float64
+        assert new_mgr.iget(2).dtype == np.object_
+        assert new_mgr.iget(3).dtype == np.int64
+        assert new_mgr.iget(4).dtype == np.float64
 
         mgr = create_mgr(
             "a,b,foo: object; f: i4; bool: bool; dt: datetime; i: i8; g: f8; h: f2"
@@ -510,15 +513,15 @@ def _compare(old_mgr, new_mgr):
         mgr.set("b", np.array(["2."] * N, dtype=np.object_))
         mgr.set("foo", np.array(["foo."] * N, dtype=np.object_))
         new_mgr = mgr.convert(numeric=True)
-        assert new_mgr.get("a").dtype == np.int64
-        assert new_mgr.get("b").dtype == np.float64
-        assert new_mgr.get("foo").dtype == np.object_
-        assert new_mgr.get("f").dtype == np.int32
-        assert new_mgr.get("bool").dtype == np.bool_
-        assert new_mgr.get("dt").dtype.type, np.datetime64
-        assert new_mgr.get("i").dtype == np.int64
-        assert new_mgr.get("g").dtype == np.float64
-        assert new_mgr.get("h").dtype == np.float16
+        assert new_mgr.iget(0).dtype == np.int64
+        assert new_mgr.iget(1).dtype == np.float64
+        assert new_mgr.iget(2).dtype == np.object_
+        assert new_mgr.iget(3).dtype == np.int32
+        assert new_mgr.iget(4).dtype == np.bool_
+        assert new_mgr.iget(5).dtype.type, np.datetime64
+        assert new_mgr.iget(6).dtype == np.int64
+        assert new_mgr.iget(7).dtype == np.float64
+        assert new_mgr.iget(8).dtype == np.float16
 
     def test_invalid_ea_block(self):
         with pytest.raises(AssertionError, match="block.size != values.size"):
@@ -620,16 +623,16 @@ def test_reindex_items(self):
         assert reindexed.nblocks == 2
         tm.assert_index_equal(reindexed.items, pd.Index(["g", "c", "a", "d"]))
         tm.assert_almost_equal(
-            mgr.get("g").internal_values(), reindexed.get("g").internal_values()
+            mgr.iget(6).internal_values(), reindexed.iget(0).internal_values()
         )
         tm.assert_almost_equal(
-            mgr.get("c").internal_values(), reindexed.get("c").internal_values()
+            mgr.iget(2).internal_values(), reindexed.iget(1).internal_values()
         )
         tm.assert_almost_equal(
-            mgr.get("a").internal_values(), reindexed.get("a").internal_values()
+            mgr.iget(0).internal_values(), reindexed.iget(2).internal_values()
         )
         tm.assert_almost_equal(
-            mgr.get("d").internal_values(), reindexed.get("d").internal_values()
+            mgr.iget(3).internal_values(), reindexed.iget(3).internal_values()
         )
 
     def test_get_numeric_data(self):
@@ -645,13 +648,15 @@ def test_get_numeric_data(self):
             numeric.items, pd.Index(["int", "float", "complex", "bool"])
         )
         tm.assert_almost_equal(
-            mgr.get("float").internal_values(), numeric.get("float").internal_values()
+            mgr.iget(mgr.items.get_loc("float")).internal_values(),
+            numeric.iget(numeric.items.get_loc("float")).internal_values(),
         )
 
         # Check sharing
         numeric.set("float", np.array([100.0, 200.0, 300.0]))
         tm.assert_almost_equal(
-            mgr.get("float").internal_values(), np.array([100.0, 200.0, 300.0])
+            mgr.iget(mgr.items.get_loc("float")).internal_values(),
+            np.array([100.0, 200.0, 300.0]),
         )
 
         numeric2 = mgr.get_numeric_data(copy=True)
@@ -660,7 +665,8 @@ def test_get_numeric_data(self):
         )
         numeric2.set("float", np.array([1000.0, 2000.0, 3000.0]))
         tm.assert_almost_equal(
-            mgr.get("float").internal_values(), np.array([100.0, 200.0, 300.0])
+            mgr.iget(mgr.items.get_loc("float")).internal_values(),
+            np.array([100.0, 200.0, 300.0]),
         )
 
     def test_get_bool_data(self):
@@ -674,19 +680,22 @@ def test_get_bool_data(self):
         bools = mgr.get_bool_data()
         tm.assert_index_equal(bools.items, pd.Index(["bool"]))
         tm.assert_almost_equal(
-            mgr.get("bool").internal_values(), bools.get("bool").internal_values()
+            mgr.iget(mgr.items.get_loc("bool")).internal_values(),
+            bools.iget(bools.items.get_loc("bool")).internal_values(),
         )
 
         bools.set("bool", np.array([True, False, True]))
         tm.assert_numpy_array_equal(
-            mgr.get("bool").internal_values(), np.array([True, False, True])
+            mgr.iget(mgr.items.get_loc("bool")).internal_values(),
+            np.array([True, False, True]),
         )
 
         # Check sharing
         bools2 = mgr.get_bool_data(copy=True)
         bools2.set("bool", np.array([False, True, False]))
         tm.assert_numpy_array_equal(
-            mgr.get("bool").internal_values(), np.array([True, False, True])
+            mgr.iget(mgr.items.get_loc("bool")).internal_values(),
+            np.array([True, False, True]),
         )
 
     def test_unicode_repr_doesnt_raise(self):