CLN: simplify Styler._translate (#43686)

Author: attack68

doc/source/user_guide/style.ipynb

@@ -1047,7 +1047,7 @@
    "source": [
     "### 5. If every byte counts use string replacement\n",
     "\n",
-    "You can remove unnecessary HTML, or shorten the default class names with string replace functions."
+    "You can remove unnecessary HTML, or shorten the default class names by replacing the default css dict. You can read a little more about CSS [below](#More-About-CSS-and-HTML)."
    ]
   },
   {
@@ -1056,21 +1056,24 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "html = Styler(df4, uuid_len=0, cell_ids=False)\\\n",
-    "      .set_table_styles([{'selector': 'td', 'props': props},\n",
-    "                         {'selector': '.col1', 'props': 'color:green;'},\n",
-    "                         {'selector': '.level0', 'props': 'color:blue;'}])\\\n",
-    "      .to_html()\\\n",
-    "      .replace('blank', '')\\\n",
-    "      .replace('data', '')\\\n",
-    "      .replace('level0', 'l0')\\\n",
-    "      .replace('col_heading', '')\\\n",
-    "      .replace('row_heading', '')\n",
-    "\n",
-    "import re\n",
-    "html = re.sub(r'col[0-9]+', lambda x: x.group().replace('col', 'c'), html)\n",
-    "html = re.sub(r'row[0-9]+', lambda x: x.group().replace('row', 'r'), html)\n",
-    "print(html)"
+    "my_css = {\n",
+    "    \"row_heading\": \"\",\n",
+    "    \"col_heading\": \"\",\n",
+    "    \"index_name\": \"\",\n",
+    "    \"col\": \"c\",\n",
+    "    \"row\": \"r\",\n",
+    "    \"col_trim\": \"\",\n",
+    "    \"row_trim\": \"\",\n",
+    "    \"level\": \"l\",\n",
+    "    \"data\": \"\",\n",
+    "    \"blank\": \"\",\n",
+    "}\n",
+    "html = Styler(df4, uuid_len=0, cell_ids=False)\n",
+    "html.set_table_styles([{'selector': 'td', 'props': props},\n",
+    "                       {'selector': '.c1', 'props': 'color:green;'},\n",
+    "                       {'selector': '.l0', 'props': 'color:blue;'}],\n",
+    "                      css_class_names=my_css)\n",
+    "print(html.to_html())"
    ]
   },
   {
@@ -1079,8 +1082,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from IPython.display import HTML\n",
-    "HTML(html)"
+    "html"
    ]
   },
   {
@@ -1658,6 +1660,7 @@
     "  + `row<m>`, where `m` is the numeric position of the cell.\n",
     "  + `col<n>`, where `n` is the numeric position of the cell.\n",
     "- Blank cells include `blank`\n",
+    "- Trimmed cells include `col_trim` or `row_trim`\n",
     "\n",
     "The structure of the `id` is `T_uuid_level<k>_row<m>_col<n>` where `level<k>` is used only on headings, and headings will only have either `row<m>` or `col<n>` whichever is needed. By default we've also prepended each row/column identifier with a UUID unique to each DataFrame so that the style from one doesn't collide with the styling from another within the same notebook or page. You can read more about the use of UUIDs in [Optimization](#Optimization).\n",
     "\n",
@@ -2020,7 +2023,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3 (ipykernel)",
    "language": "python",
    "name": "python3"
   },
@@ -2034,7 +2037,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.6"
+   "version": "3.9.5"
   }
  },
  "nbformat": 4,

doc/source/whatsnew/v1.4.0.rst

@@ -80,6 +80,7 @@ Styler
   - Global options have been extended to configure default ``Styler`` properties including formatting and encoding and mathjax options and LaTeX (:issue:`41395`)
   - Naive sparsification is now possible for LaTeX without the multirow package (:issue:`43369`)
   - :meth:`Styler.to_html` omits CSSStyle rules for hidden table elements (:issue:`43619`)
+  - Custom CSS classes can now be directly specified without string replacement (:issue:`43686`)
 
 Formerly Styler relied on ``display.html.use_mathjax``, which has now been replaced by ``styler.html.mathjax``.
 

pandas/io/formats/style.py

@@ -146,7 +146,10 @@ class Styler(StylerRenderer):
     Attributes
     ----------
     env : Jinja2 jinja2.Environment
-    template : Jinja2 Template
+    template_html : Jinja2 Template
+    template_html_table : Jinja2 Template
+    template_html_style : Jinja2 Template
+    template_latex : Jinja2 Template
     loader : Jinja2 Loader
 
     See Also
@@ -182,6 +185,11 @@ class Styler(StylerRenderer):
 
     * Blank cells include ``blank``
     * Data cells include ``data``
+    * Trimmed cells include ``col_trim`` or ``row_trim``.
+
+    Any, or all, or these classes can be renamed by using the ``css_class_names``
+    argument in ``Styler.set_table_classes``, giving a value such as
+    *{"row": "MY_ROW_CLASS", "col_trim": "", "row_trim": ""}*.
     """
 
     def __init__(
@@ -1159,6 +1167,7 @@ def _copy(self, deepcopy: bool = False) -> Styler:
           - caption
 
         Non-data dependent attributes [copied and exported]:
+          - css
           - hidden index state and hidden columns state (.hide_index_, .hide_columns_)
           - table_attributes
           - table_styles
@@ -1185,6 +1194,7 @@ def _copy(self, deepcopy: bool = False) -> Styler:
             "template_html",
         ]
         deep = [  # nested lists or dicts
+            "css",
             "_display_funcs",
             "_display_funcs_index",
             "_display_funcs_columns",
@@ -1948,9 +1958,10 @@ def set_sticky(
 
     def set_table_styles(
         self,
-        table_styles: dict[Any, CSSStyles] | CSSStyles,
+        table_styles: dict[Any, CSSStyles] | CSSStyles | None = None,
         axis: int = 0,
         overwrite: bool = True,
+        css_class_names: dict[str, str] | None = None,
     ) -> Styler:
         """
         Set the table styles included within the ``<style>`` HTML element.
@@ -1990,6 +2001,11 @@ def set_table_styles(
 
             .. versionadded:: 1.2.0
 
+        css_class_names : dict, optional
+            A dict of strings used to replace the default CSS classes described below.
+
+            .. versionadded:: 1.4.0
+
         Returns
         -------
         self : Styler
@@ -2001,6 +2017,22 @@ def set_table_styles(
         Styler.set_table_attributes: Set the table attributes added to the ``<table>``
             HTML element.
 
+        Notes
+        -----
+        The default CSS classes dict, whose values can be replaced is as follows:
+
+        .. code-block:: python
+
+            css_class_names = {"row_heading": "row_heading",
+                               "col_heading": "col_heading",
+                               "index_name": "index_name",
+                               "col": "col",
+                               "col_trim": "col_trim",
+                               "row_trim": "row_trim",
+                               "level": "level",
+                               "data": "data",
+                               "blank": "blank}
+
         Examples
         --------
         >>> df = pd.DataFrame(np.random.randn(10, 4),
@@ -2036,10 +2068,15 @@ def set_table_styles(
         See `Table Visualization <../../user_guide/style.ipynb>`_ user guide for
         more details.
         """
-        if isinstance(table_styles, dict):
+        if css_class_names is not None:
+            self.css = {**self.css, **css_class_names}
+
+        if table_styles is None:
+            return self
+        elif isinstance(table_styles, dict):
             axis = self.data._get_axis_number(axis)
             obj = self.data.index if axis == 1 else self.data.columns
-            idf = ".row" if axis == 1 else ".col"
+            idf = f".{self.css['row']}" if axis == 1 else f".{self.css['col']}"
 
             table_styles = [
                 {