TYP: Postponed Evaluation of Annotations (PEP 563) (#36034)

Author: simonjayhawkins

pandas/core/algorithms.py

@@ -2,6 +2,8 @@
 Generic data algorithms. This module is experimental at the moment and not
 intended for public consumption
 """
+from __future__ import annotations
+
 import operator
 from textwrap import dedent
 from typing import TYPE_CHECKING, Dict, Optional, Tuple, Union
@@ -707,7 +709,7 @@ def value_counts(
     normalize: bool = False,
     bins=None,
     dropna: bool = True,
-) -> "Series":
+) -> Series:
     """
     Compute a histogram of the counts of non-null values.
 
@@ -849,7 +851,7 @@ def duplicated(values, keep="first") -> np.ndarray:
     return f(values, keep=keep)
 
 
-def mode(values, dropna: bool = True) -> "Series":
+def mode(values, dropna: bool = True) -> Series:
     """
     Returns the mode(s) of an array.
 
@@ -1161,7 +1163,7 @@ class SelectNSeries(SelectN):
     nordered : Series
     """
 
-    def compute(self, method: str) -> "Series":
+    def compute(self, method: str) -> Series:
 
         n = self.n
         dtype = self.obj.dtype
@@ -1235,7 +1237,7 @@ def __init__(self, obj, n: int, keep: str, columns):
         columns = list(columns)
         self.columns = columns
 
-    def compute(self, method: str) -> "DataFrame":
+    def compute(self, method: str) -> DataFrame:
 
         from pandas import Int64Index
 

pandas/core/construction.py

@@ -4,6 +4,7 @@
 
 These should not depend on core.internals.
 """
+from __future__ import annotations
 
 from collections import abc
 from typing import TYPE_CHECKING, Any, Optional, Sequence, Union, cast
@@ -49,16 +50,14 @@
 import pandas.core.common as com
 
 if TYPE_CHECKING:
-    from pandas.core.arrays import ExtensionArray  # noqa: F401
-    from pandas.core.indexes.api import Index  # noqa: F401
-    from pandas.core.series import Series  # noqa: F401
+    from pandas import ExtensionArray, Index, Series
 
 
 def array(
     data: Union[Sequence[object], AnyArrayLike],
     dtype: Optional[Dtype] = None,
     copy: bool = True,
-) -> "ExtensionArray":
+) -> ExtensionArray:
     """
     Create an array.
 
@@ -389,7 +388,7 @@ def extract_array(obj, extract_numpy: bool = False):
 
 def sanitize_array(
     data,
-    index: Optional["Index"],
+    index: Optional[Index],
     dtype: Optional[DtypeObj] = None,
     copy: bool = False,
     raise_cast_failure: bool = False,
@@ -594,13 +593,13 @@ def is_empty_data(data: Any) -> bool:
 
 def create_series_with_explicit_dtype(
     data: Any = None,
-    index: Optional[Union[ArrayLike, "Index"]] = None,
+    index: Optional[Union[ArrayLike, Index]] = None,
     dtype: Optional[Dtype] = None,
     name: Optional[str] = None,
     copy: bool = False,
     fastpath: bool = False,
     dtype_if_empty: Dtype = object,
-) -> "Series":
+) -> Series:
     """
     Helper to pass an explicit dtype when instantiating an empty Series.
 

pandas/core/frame.py

@@ -8,6 +8,7 @@
 alignment and a host of useful data manipulation methods having to do with the
 labeling information
 """
+from __future__ import annotations
 
 import collections
 from collections import abc
@@ -885,7 +886,7 @@ def to_string(
     # ----------------------------------------------------------------------
 
     @property
-    def style(self) -> "Styler":
+    def style(self) -> Styler:
         """
         Returns a Styler object.
 
@@ -6530,7 +6531,7 @@ def groupby(
         squeeze: bool = no_default,
         observed: bool = False,
         dropna: bool = True,
-    ) -> "DataFrameGroupBy":
+    ) -> DataFrameGroupBy:
         from pandas.core.groupby.generic import DataFrameGroupBy
 
         if squeeze is not no_default:

pandas/core/generic.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import collections
 from datetime import timedelta
 import functools
@@ -110,7 +112,7 @@
     from pandas._libs.tslibs import BaseOffset
 
     from pandas.core.resample import Resampler
-    from pandas.core.series import Series  # noqa: F401
+    from pandas.core.series import Series
     from pandas.core.window.indexers import BaseIndexer
 
 # goal is to be able to define the docs close to function, while still being
@@ -391,7 +393,7 @@ def _get_block_manager_axis(cls, axis: Axis) -> int:
             return m - axis
         return axis
 
-    def _get_axis_resolvers(self, axis: str) -> Dict[str, Union["Series", MultiIndex]]:
+    def _get_axis_resolvers(self, axis: str) -> Dict[str, Union[Series, MultiIndex]]:
         # index or columns
         axis_index = getattr(self, axis)
         d = dict()
@@ -421,10 +423,10 @@ def _get_axis_resolvers(self, axis: str) -> Dict[str, Union["Series", MultiIndex
         d[axis] = dindex
         return d
 
-    def _get_index_resolvers(self) -> Dict[str, Union["Series", MultiIndex]]:
+    def _get_index_resolvers(self) -> Dict[str, Union[Series, MultiIndex]]:
         from pandas.core.computation.parsing import clean_column_name
 
-        d: Dict[str, Union["Series", MultiIndex]] = {}
+        d: Dict[str, Union[Series, MultiIndex]] = {}
         for axis_name in self._AXIS_ORDERS:
             d.update(self._get_axis_resolvers(axis_name))
 
@@ -660,7 +662,7 @@ def droplevel(self: FrameOrSeries, level, axis=0) -> FrameOrSeries:
         result = self.set_axis(new_labels, axis=axis, inplace=False)
         return result
 
-    def pop(self, item: Label) -> Union["Series", Any]:
+    def pop(self, item: Label) -> Union[Series, Any]:
         result = self[item]
         del self[item]
         if self.ndim == 2:
@@ -7684,7 +7686,7 @@ def resample(
         level=None,
         origin: Union[str, TimestampConvertibleTypes] = "start_day",
         offset: Optional[TimedeltaConvertibleTypes] = None,
-    ) -> "Resampler":
+    ) -> Resampler:
         """
         Resample time-series data.
 
@@ -10457,7 +10459,7 @@ def mad(self, axis=None, skipna=None, level=None):
     @doc(Rolling)
     def rolling(
         self,
-        window: "Union[int, timedelta, BaseOffset, BaseIndexer]",
+        window: Union[int, timedelta, BaseOffset, BaseIndexer],
         min_periods: Optional[int] = None,
         center: bool_t = False,
         win_type: Optional[str] = None,