pandas-devgh-544: Fix pd.options.display.float_format (pandas-dev#545)

Set the correct type for pd.options.display.float_format.

Resolves pandas-dev#544

Author: m-pilia

pandas-stubs/_config/config.pyi

@@ -1,4 +1,7 @@
-from collections.abc import Iterable
+from collections.abc import (
+    Callable,
+    Iterable,
+)
 from contextlib import ContextDecorator
 from typing import (
     Any,
@@ -51,7 +54,7 @@ class Display(DictWrapper):
     date_yearfirst: bool
     encoding: str
     expand_frame_repr: bool
-    float_format: str | None
+    float_format: Callable[[float], str] | None
     html: DisplayHTML
     large_repr: str
     latex: DisplayLaTeX

tests/test_config.py

@@ -1,6 +1,8 @@
 from typing import (
     TYPE_CHECKING,
     Any,
+    Callable,
+    Optional,
 )
 
 import pandas as pd
@@ -36,3 +38,13 @@ def test_specific_option():
     check(assert_type(pd.options.plotting.backend, str), str)
     # Just check assignment
     pd.options.plotting.backend = "matplotlib"
+
+
+def test_display_float_format():
+    check(
+        assert_type(pd.options.display.float_format, Optional[Callable[[float], str]]),
+        type(None),
+    )
+    formatter = "{,.2f}".format
+    with pd.option_context("display.float_format", formatter):
+        assert pd.get_option("display.float_format") == formatter