REF: share Index subclass formatting code (#44070)

Author: jbrockmendel

pandas/core/indexes/base.py

@@ -1247,11 +1247,11 @@ def _format_data(self, name=None) -> str_t:
             line_break_each_value=self._is_multi,
         )
 
-    def _format_attrs(self) -> list[tuple[str_t, str_t | int]]:
+    def _format_attrs(self) -> list[tuple[str_t, str_t | int | bool | None]]:
         """
         Return a list of tuples of the (attr,formatted_value).
         """
-        attrs: list[tuple[str_t, str_t | int]] = []
+        attrs: list[tuple[str_t, str_t | int | bool | None]] = []
 
         if not self._is_multi:
             attrs.append(("dtype", f"'{self.dtype}'"))
@@ -1295,9 +1295,7 @@ def format(
 
         return self._format_with_header(header, na_rep=na_rep)
 
-    def _format_with_header(
-        self, header: list[str_t], na_rep: str_t = "NaN"
-    ) -> list[str_t]:
+    def _format_with_header(self, header: list[str_t], na_rep: str_t) -> list[str_t]:
         from pandas.io.formats.format import format_array
 
         values = self._values
@@ -1387,9 +1385,16 @@ def _summary(self, name=None) -> str_t:
             head = self[0]
             if hasattr(head, "format") and not isinstance(head, str):
                 head = head.format()
+            elif needs_i8_conversion(self.dtype):
+                # e.g. Timedelta, display as values, not quoted
+                head = self._formatter_func(head).replace("'", "")
             tail = self[-1]
             if hasattr(tail, "format") and not isinstance(tail, str):
                 tail = tail.format()
+            elif needs_i8_conversion(self.dtype):
+                # e.g. Timedelta, display as values, not quoted
+                tail = self._formatter_func(tail).replace("'", "")
+
             index_summary = f", {head} to {tail}"
         else:
             index_summary = ""

pandas/core/indexes/category.py

@@ -44,6 +44,8 @@
     inherit_names,
 )
 
+from pandas.io.formats.printing import pprint_thing
+
 _index_doc_kwargs: dict[str, str] = dict(ibase._index_doc_kwargs)
 _index_doc_kwargs.update({"target_klass": "CategoricalIndex"})
 
@@ -180,6 +182,7 @@ def _can_hold_strings(self):
 
     codes: np.ndarray
     categories: Index
+    ordered: bool | None
     _data: Categorical
     _values: Categorical
 
@@ -342,20 +345,18 @@ def _format_attrs(self):
             if get_option("display.max_categories") == 0
             else get_option("display.max_categories")
         )
+        attrs: list[tuple[str, str | int | bool | None]]
         attrs = [
             (
                 "categories",
                 ibase.default_pprint(self.categories, max_seq_items=max_categories),
             ),
-            # error: "CategoricalIndex" has no attribute "ordered"
-            ("ordered", self.ordered),  # type: ignore[attr-defined]
+            ("ordered", self.ordered),
         ]
         extra = super()._format_attrs()
         return attrs + extra
 
-    def _format_with_header(self, header: list[str], na_rep: str = "NaN") -> list[str]:
-        from pandas.io.formats.printing import pprint_thing
-
+    def _format_with_header(self, header: list[str], na_rep: str) -> list[str]:
         result = [
             pprint_thing(x, escape_chars=("\t", "\r", "\n")) if notna(x) else na_rep
             for x in self._values

pandas/core/indexes/datetimelike.py

@@ -188,6 +188,7 @@ def format(
     def _format_with_header(
         self, header: list[str], na_rep: str = "NaT", date_format: str | None = None
     ) -> list[str]:
+        # matches base class except for whitespace padding and date_format
         return header + list(
             self._format_native_types(na_rep=na_rep, date_format=date_format)
         )
@@ -207,39 +208,15 @@ def _format_attrs(self):
                 freq = self.freqstr
                 if freq is not None:
                     freq = repr(freq)  # e.g. D -> 'D'
-                # Argument 1 to "append" of "list" has incompatible type
-                # "Tuple[str, Optional[str]]"; expected "Tuple[str, Union[str, int]]"
-                attrs.append(("freq", freq))  # type: ignore[arg-type]
+                attrs.append(("freq", freq))
         return attrs
 
+    @Appender(Index._summary.__doc__)
     def _summary(self, name=None) -> str:
-        """
-        Return a summarized representation.
-
-        Parameters
-        ----------
-        name : str
-            Name to use in the summary representation.
-
-        Returns
-        -------
-        str
-            Summarized representation of the index.
-        """
-        formatter = self._formatter_func
-        if len(self) > 0:
-            index_summary = f", {formatter(self[0])} to {formatter(self[-1])}"
-        else:
-            index_summary = ""
-
-        if name is None:
-            name = type(self).__name__
-        result = f"{name}: {len(self)} entries{index_summary}"
+        result = super()._summary(name=name)
         if self.freq:
             result += f"\nFreq: {self.freqstr}"
 
-        # display as values, not quoted
-        result = result.replace("'", "")
         return result
 
     # --------------------------------------------------------------------

pandas/core/indexes/interval.py

@@ -800,7 +800,8 @@ def length(self) -> Index:
     # Rendering Methods
     # __repr__ associated methods are based on MultiIndex
 
-    def _format_with_header(self, header: list[str], na_rep: str = "NaN") -> list[str]:
+    def _format_with_header(self, header: list[str], na_rep: str) -> list[str]:
+        # matches base class except for whitespace padding
         return header + list(self._format_native_types(na_rep=na_rep))
 
     def _format_native_types(self, na_rep="NaN", quoting=None, **kwargs):

pandas/core/indexes/range.py

@@ -214,7 +214,8 @@ def _format_data(self, name=None):
         # we are formatting thru the attributes
         return None
 
-    def _format_with_header(self, header: list[str], na_rep: str = "NaN") -> list[str]:
+    def _format_with_header(self, header: list[str], na_rep: str) -> list[str]:
+        # Equivalent to Index implementation, but faster
         if not len(self._range):
             return header
         first_val_str = str(self._range[0])