BUG: DataFrame.to_html ignores formatters (#37958)

Author: ma3da

doc/source/whatsnew/v1.2.0.rst

@@ -656,6 +656,7 @@ I/O
 - Bug in :meth:`read_fw` was not skipping blank lines (even with ``skip_blank_lines=True``) (:issue:`37758`)
 - Parse missing values using :func:`read_json` with ``dtype=False`` to ``NaN`` instead of ``None`` (:issue:`28501`)
 - :meth:`read_fwf` was inferring compression with ``compression=None`` which was not consistent with the other :meth:``read_*`` functions (:issue:`37909`)
+- :meth:`DataFrame.to_html` was ignoring ``formatters`` argument for ``ExtensionDtype`` columns (:issue:`36525`)
 
 Period
 ^^^^^^

pandas/io/formats/format.py

@@ -1537,7 +1537,9 @@ class ExtensionArrayFormatter(GenericArrayFormatter):
     def _format_strings(self) -> List[str]:
         values = extract_array(self.values, extract_numpy=True)
 
-        formatter = values._formatter(boxed=True)
+        formatter = self.formatter
+        if formatter is None:
+            formatter = values._formatter(boxed=True)
 
         if is_categorical_dtype(values.dtype):
             # Categorical is special for now, so that we can preserve tzinfo
@@ -1553,7 +1555,9 @@ def _format_strings(self) -> List[str]:
             digits=self.digits,
             space=self.space,
             justify=self.justify,
+            decimal=self.decimal,
             leading_space=self.leading_space,
+            quoting=self.quoting,
         )
         return fmt_values
 

pandas/tests/io/formats/data/html/various_dtypes_formatted.html

@@ -0,0 +1,36 @@
+<table border="1" class="dataframe">
+  <thead>
+    <tr style="text-align: right;">
+      <th></th>
+      <th>i</th>
+      <th>f</th>
+      <th>I</th>
+      <th>s</th>
+      <th>b</th>
+      <th>c</th>
+      <th>o</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th>0</th>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+    </tr>
+    <tr>
+      <th>1</th>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+      <td>formatted</td>
+    </tr>
+  </tbody>
+</table>

pandas/tests/io/formats/test_to_html.py

@@ -247,6 +247,21 @@ def test_to_html_multiindex_odd_even_truncate(max_rows, expected, datapath):
             {"hod": lambda x: x.strftime("%H:%M")},
             "datetime64_hourformatter",
         ),
+        (
+            DataFrame(
+                {
+                    "i": pd.Series([1, 2], dtype="int64"),
+                    "f": pd.Series([1, 2], dtype="float64"),
+                    "I": pd.Series([1, 2], dtype="Int64"),
+                    "s": pd.Series([1, 2], dtype="string"),
+                    "b": pd.Series([True, False], dtype="boolean"),
+                    "c": pd.Series(["a", "b"], dtype=pd.CategoricalDtype(["a", "b"])),
+                    "o": pd.Series([1, "2"], dtype=object),
+                }
+            ),
+            [lambda x: "formatted"] * 7,
+            "various_dtypes_formatted",
+        ),
     ],
 )
 def test_to_html_formatters(df, formatters, expected, datapath):