Make (Int|UInt|Float)64Index inherit from NumIndex

topper-123 · topper-123 · commit 81b014f1f25d · 2021-04-27T12:11:28.000+01:00
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
@@ -442,7 +442,7 @@ def __new__(
             return Index._simple_new(data, name=name)
 
         # index-like
-        elif isinstance(data, NumIndex) and dtype is None:
+        elif type(data) is NumIndex and dtype is None:
             return NumIndex(data, name=name, copy=copy)
         elif isinstance(data, (np.ndarray, Index, ABCSeries)):
 
@@ -5490,8 +5490,8 @@ def map(self, mapper, na_action=None):
             # empty
             attributes["dtype"] = self.dtype
 
-        if isinstance(self, NumIndex):
-            return NumIndex(new_values, **attributes)
+        if type(self) is NumIndex:
+            return type(self)(new_values, **attributes)
 
         return Index(new_values, **attributes)
 
diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
@@ -285,7 +285,7 @@ def astype(self, dtype, copy: bool = True) -> Index:
         dtype = pandas_dtype(dtype)
 
         cat = self.categories
-        if isinstance(cat, NumIndex):
+        if type(cat) is NumIndex:
             try:
                 cat._validate_dtype(dtype)
             except ValueError:
diff --git a/pandas/core/indexes/numeric.py b/pandas/core/indexes/numeric.py
@@ -55,7 +55,7 @@ class NumericIndex(Index):
     """
 
     _values: np.ndarray
-    _default_dtype: np.dtype
+    _default_dtype: np.dtype | None = None
     _dtype_validation_metadata: tuple[Callable[..., bool], str]
 
     _is_numeric_dtype = True
@@ -88,7 +88,10 @@ def _ensure_array(cls, data, dtype, copy: bool):
         if issubclass(data.dtype.type, str):
             cls._string_data_error(data)
 
-        if copy or not is_dtype_equal(data.dtype, cls._default_dtype):
+        if copy or (
+            cls._default_dtype is not None
+            and not is_dtype_equal(data.dtype, cls._default_dtype)
+        ):
             subarr = np.array(data, dtype=cls._default_dtype, copy=copy)
             cls._assert_safe_casting(data, subarr)
         else:
@@ -202,173 +205,6 @@ def _is_all_dates(self) -> bool:
     An Index instance can **only** contain hashable objects.
 """
 
-_int64_descr_args = {
-    "klass": "Int64Index",
-    "ltype": "integer",
-    "dtype": "int64",
-    "extra": "",
-}
-
-
-class IntegerIndex(NumericIndex):
-    """
-    This is an abstract class for Int64Index, UInt64Index.
-    """
-
-    _default_dtype: np.dtype
-    _can_hold_na = False
-
-    @classmethod
-    def _assert_safe_casting(cls, data, subarr):
-        """
-        Ensure incoming data can be represented with matching signed-ness.
-        """
-        if data.dtype.kind != cls._default_dtype.kind:
-            if not np.array_equal(data, subarr):
-                raise TypeError("Unsafe NumPy casting, you must explicitly cast")
-
-    def __contains__(self, key) -> bool:
-        """
-        Check if key is a float and has a decimal. If it has, return False.
-        """
-        hash(key)
-        try:
-            if is_float(key) and int(key) != key:
-                # otherwise the `key in self._engine` check casts e.g. 1.1 -> 1
-                return False
-            return key in self._engine
-        except (OverflowError, TypeError, ValueError):
-            return False
-
-    @property
-    def inferred_type(self) -> str:
-        """
-        Always 'integer' for ``Int64Index`` and ``UInt64Index``
-        """
-        return "integer"
-
-    @property
-    def asi8(self) -> np.ndarray:
-        # do not cache or you'll create a memory leak
-        warnings.warn(
-            "Index.asi8 is deprecated and will be removed in a future version",
-            FutureWarning,
-            stacklevel=2,
-        )
-        return self._values.view(self._default_dtype)
-
-
-class Int64Index(IntegerIndex):
-    __doc__ = _num_index_shared_docs["class_descr"] % _int64_descr_args
-
-    _typ = "int64index"
-    _engine_type = libindex.Int64Engine
-    _default_dtype = np.dtype(np.int64)
-    _dtype_validation_metadata = (is_signed_integer_dtype, "signed integer")
-
-
-_uint64_descr_args = {
-    "klass": "UInt64Index",
-    "ltype": "unsigned integer",
-    "dtype": "uint64",
-    "extra": "",
-}
-
-
-class UInt64Index(IntegerIndex):
-    __doc__ = _num_index_shared_docs["class_descr"] % _uint64_descr_args
-
-    _typ = "uint64index"
-    _engine_type = libindex.UInt64Engine
-    _default_dtype = np.dtype(np.uint64)
-    _dtype_validation_metadata = (is_unsigned_integer_dtype, "unsigned integer")
-
-    # ----------------------------------------------------------------
-    # Indexing Methods
-
-    @doc(Index._convert_arr_indexer)
-    def _convert_arr_indexer(self, keyarr):
-        # Cast the indexer to uint64 if possible so that the values returned
-        # from indexing are also uint64.
-        dtype = None
-        if is_integer_dtype(keyarr) or (
-            lib.infer_dtype(keyarr, skipna=False) == "integer"
-        ):
-            dtype = np.dtype(np.uint64)
-
-        return com.asarray_tuplesafe(keyarr, dtype=dtype)
-
-
-_float64_descr_args = {
-    "klass": "Float64Index",
-    "dtype": "float64",
-    "ltype": "float",
-    "extra": "",
-}
-
-
-class Float64Index(NumericIndex):
-    __doc__ = _num_index_shared_docs["class_descr"] % _float64_descr_args
-
-    _typ = "float64index"
-    _engine_type = libindex.Float64Engine
-    _default_dtype = np.dtype(np.float64)
-    _dtype_validation_metadata = (is_float_dtype, "float")
-
-    @property
-    def inferred_type(self) -> str:
-        """
-        Always 'floating' for ``Float64Index``
-        """
-        return "floating"
-
-    @doc(Index.astype)
-    def astype(self, dtype, copy=True):
-        dtype = pandas_dtype(dtype)
-        if needs_i8_conversion(dtype):
-            raise TypeError(
-                f"Cannot convert Float64Index to dtype {dtype}; integer "
-                "values are required for conversion"
-            )
-        elif is_integer_dtype(dtype) and not is_extension_array_dtype(dtype):
-            # TODO(jreback); this can change once we have an EA Index type
-            # GH 13149
-            arr = astype_nansafe(self._values, dtype=dtype)
-            return Int64Index(arr, name=self.name)
-        return super().astype(dtype, copy=copy)
-
-    # ----------------------------------------------------------------
-    # Indexing Methods
-
-    @doc(Index._should_fallback_to_positional)
-    def _should_fallback_to_positional(self) -> bool:
-        return False
-
-    @doc(Index._convert_slice_indexer)
-    def _convert_slice_indexer(self, key: slice, kind: str):
-        assert kind in ["loc", "getitem"]
-
-        # We always treat __getitem__ slicing as label-based
-        # translate to locations
-        return self.slice_indexer(key.start, key.stop, key.step, kind=kind)
-
-    # ----------------------------------------------------------------
-
-    def _format_native_types(
-        self, na_rep="", float_format=None, decimal=".", quoting=None, **kwargs
-    ):
-        from pandas.io.formats.format import FloatArrayFormatter
-
-        formatter = FloatArrayFormatter(
-            self._values,
-            na_rep=na_rep,
-            float_format=float_format,
-            decimal=decimal,
-            quoting=quoting,
-            fixed_width=False,
-        )
-        return formatter.get_result_as_array()
-
 
 _numindex_descr_args = {
     "klass": "NumIndex",
@@ -382,7 +218,6 @@ class NumIndex(NumericIndex):
     __doc__ = _num_index_shared_docs["class_descr"] % _numindex_descr_args
 
     _typ = "numindex"
-    _default_dtype: np.dtype
     _dtype_validation_metadata = (is_numeric_dtype, "numeric type")
 
     @cache_readonly
@@ -416,21 +251,13 @@ def inferred_type(self) -> str:
         }[self.dtype.kind]
 
     @classmethod
-    def _ensure_array(cls, data, dtype, copy: bool) -> np.ndarray:
-        """
-        Ensure we have a valid array to pass to _simple_new.
-        """
-        arr = np.array(data, dtype=dtype, copy=copy)
-        cls._validate_dtype(arr.dtype)
-        return arr
-
-    @classmethod
-    def _assert_safe_casting(cls, data, subarr):
+    def _assert_safe_casting(cls, data, subarr) -> None:
         """
         Ensure incoming data can be represented with matching signed-ness.
         """
-        if data.dtype.kind not in {"i", "u"} and not np.array_equal(data, subarr):
-            raise TypeError("Unsafe NumPy casting, you must explicitly cast")
+        if is_integer_dtype(subarr.dtype):
+            if not np.array_equal(data, subarr):
+                raise TypeError("Unsafe NumPy casting, you must explicitly cast")
 
     def __contains__(self, key) -> bool:
         """
@@ -450,11 +277,7 @@ def __contains__(self, key) -> bool:
 
     @doc(Index.astype)
     def astype(self, dtype, copy=True):
-        if is_categorical_dtype(dtype):
-            from pandas import CategoricalIndex
-
-            return CategoricalIndex(self, name=self.name, dtype=dtype, copy=copy)
-        elif is_float_dtype(dtype):
+        if is_float_dtype(self.dtype):
             dtype = pandas_dtype(dtype)
             if needs_i8_conversion(dtype):
                 raise TypeError(
@@ -465,17 +288,52 @@ def astype(self, dtype, copy=True):
                 # TODO(jreback); this can change once we have an EA Index type
                 # GH 13149
                 arr = astype_nansafe(self._values, dtype=dtype)
-                return type(self)(arr, name=self.name, dtype=dtype)
+                if isinstance(self, Float64Index):
+                    return Int64Index(arr, name=self.name)
+                else:
+                    return NumIndex(arr, name=self.name, dtype=dtype)
+        elif is_categorical_dtype(dtype):
+            from pandas import CategoricalIndex
+
+            return CategoricalIndex(self, name=self.name, dtype=dtype, copy=copy)
 
         return super().astype(dtype, copy=copy)
 
+    # ----------------------------------------------------------------
+    # Indexing Methods
+
+    @doc(Index._should_fallback_to_positional)
+    def _should_fallback_to_positional(self) -> bool:
+        if self.inferred_type == "floating":
+            return False
+
+        return super()._should_fallback_to_positional()
+
     @doc(Index._convert_slice_indexer)
     def _convert_slice_indexer(self, key: slice, kind: str):
-        assert kind in ["loc", "getitem"]
+        if is_float_dtype(self.dtype):
+            assert kind in ["loc", "getitem"]
+
+            # We always treat __getitem__ slicing as label-based
+            # translate to locations
+            return self.slice_indexer(key.start, key.stop, key.step, kind=kind)
+
+        return super()._convert_slice_indexer(key, kind=kind)
+
+    @doc(Index._convert_arr_indexer)
+    def _convert_arr_indexer(self, keyarr) -> np.ndarray:
+        if is_unsigned_integer_dtype(self.dtype):
+            # Cast the indexer to uint64 if possible so that the values returned
+            # from indexing are also uint64.
+            dtype = None
+            if is_integer_dtype(keyarr) or (
+                lib.infer_dtype(keyarr, skipna=False) == "integer"
+            ):
+                dtype = np.dtype(np.uint64)
 
-        # We always treat __getitem__ slicing as label-based
-        # translate to locations
-        return self.slice_indexer(key.start, key.stop, key.step, kind=kind)
+            return com.asarray_tuplesafe(keyarr, dtype=dtype)
+
+        return super()._convert_arr_indexer(keyarr)
 
     # ----------------------------------------------------------------
 
@@ -502,3 +360,67 @@ def _format_native_types(
             fixed_width=False,
         )
         return formatter.get_result_as_array()
+
+
+_int64_descr_args = {
+    "klass": "Int64Index",
+    "ltype": "integer",
+    "dtype": "int64",
+    "extra": "",
+}
+
+
+class Int64Index(NumIndex):
+    __doc__ = _num_index_shared_docs["class_descr"] % _int64_descr_args
+
+    _typ = "int64index"
+    _engine_type = libindex.Int64Engine
+    _default_dtype = np.dtype(np.int64)
+    _dtype_validation_metadata = (is_signed_integer_dtype, "signed integer")
+
+    @property
+    def asi8(self) -> np.ndarray:
+        # do not cache or you'll create a memory leak
+        warnings.warn(
+            "Index.asi8 is deprecated and will be removed in a future version",
+            FutureWarning,
+            stacklevel=2,
+        )
+        return self._values.view(self._default_dtype)
+
+
+_uint64_descr_args = {
+    "klass": "UInt64Index",
+    "ltype": "unsigned integer",
+    "dtype": "uint64",
+    "extra": "",
+}
+
+
+class UInt64Index(NumIndex):
+    __doc__ = _num_index_shared_docs["class_descr"] % _uint64_descr_args
+
+    _typ = "uint64index"
+    _engine_type = libindex.UInt64Engine
+    _default_dtype = np.dtype(np.uint64)
+    _dtype_validation_metadata = (is_unsigned_integer_dtype, "unsigned integer")
+
+    # ----------------------------------------------------------------
+    # Indexing Methods
+
+
+_float64_descr_args = {
+    "klass": "Float64Index",
+    "dtype": "float64",
+    "ltype": "float",
+    "extra": "",
+}
+
+
+class Float64Index(NumIndex):
+    __doc__ = _num_index_shared_docs["class_descr"] % _float64_descr_args
+
+    _typ = "float64index"
+    _engine_type = libindex.Float64Engine
+    _default_dtype = np.dtype(np.float64)
+    _dtype_validation_metadata = (is_float_dtype, "float")
diff --git a/pandas/tests/indexes/test_base.py b/pandas/tests/indexes/test_base.py
