BUG/ENH: Translate CSS border properties for Styler.to_excel

doc/source/user_guide/style.ipynb

@@ -1577,6 +1577,9 @@
  "Some support (*since version 0.20.0*) is available for exporting styled `DataFrames` to Excel worksheets using the `OpenPyXL` or `XlsxWriter` engines. CSS2.2 properties handled include:\n",
  "\n",
  "- `background-color`\n",
+ "- `border-style` properties\n",
+ "- `border-width` properties\n",
+ "- `border-color` properties\n",
  "- `color`\n",
  "- `font-family`\n",
  "- `font-style`\n",
@@ -1587,7 +1590,7 @@
  "- `white-space: nowrap`\n",
  "\n",
  "\n",
- "- Currently broken: `border-style`, `border-width`, `border-color` and their {`top`, `right`, `bottom`, `left` variants}\n",
+ "- Shorthand and side-specific border properties are supported (e.g. `border-style` and `border-left-style`) as well as the `border` shorthands for all sides (`border: 1px solid green`) or specified sides (`border-left: 1px solid green`). Using a `border` shorthand will override any border properties set before it (See [CSS Working Group](https://drafts.csswg.org/css-backgrounds/#border-shorthands) for more details)\n",
  "\n",
  "\n",
  "- Only CSS2 named colors and hex colors of the form `#rgb` or `#rrggbb` are currently supported.\n",

doc/source/whatsnew/v1.5.0.rst

@@ -20,6 +20,7 @@ Styler
 ^^^^^^
 
  - New method :meth:`.Styler.to_string` for alternative customisable output methods (:issue:`44502`)
+ - Added the ability to render `border` and `border-{side}` CSS properties in Excel (:issue:`42276`)
 
 .. _whatsnew_150.enhancements.enhancement2:
 
@@ -43,8 +44,10 @@ These are bug fixes that might have notable behavior changes.
 
 .. _whatsnew_150.notable_bug_fixes.notable_bug_fix1:
 
-notable_bug_fix1
-^^^^^^^^^^^^^^^^
+Styler
+^^^^^^
+
+- Fixed bug in :class:`CSSToExcelConverter` leading to ``TypeError`` when border color provided without border style for ``xlsxwriter`` engine (:issue:`42276`)
 
 .. _whatsnew_150.notable_bug_fixes.notable_bug_fix2:
 

pandas/io/formats/css.py

@@ -4,6 +4,7 @@
 from __future__ import annotations
 
 import re
+from typing import Callable
 import warnings
 
 
@@ -13,8 +14,36 @@ class CSSWarning(UserWarning):
  """
 
 
-def _side_expander(prop_fmt: str):
+def _side_expander(prop_fmt: str) -> Callable:
+ """
+ Wrapper to expand shorthand property into top, right, bottom, left properties
+
+ Parameters
+ ----------
+ side : str
+ The border side to expand into properties
+
+ Returns
+ -------
+ function: Return to call when a 'border(-{side}): {value}' string is encountered
+
+ Notes
+ -----
+ Description of [shorthand](https://developer.mozilla.org/en-US/docs/Web/CSS/Shorthand_properties) syntax
+ """
  def expand(self, prop, value: str):
+ """
+ Expand shorthand property into side-specific property (top, right, bottom, left)
+
+ Parameters
+ ----------
+ prop (str): CSS property name
+ value (str): String token for property
+
+ Yields
+ ------
+ Tuple (str, str): Expanded property, value
+ """
  tokens = value.split()
  try:
  mapping = self.SIDE_SHORTHANDS[len(tokens)]
@@ -27,12 +56,72 @@ def expand(self, prop, value: str):
  return expand
 
 
+def _border_expander(side: str = "") -> Callable:
+ """
+ Wrapper to expand 'border' property into border color, style, and width properties
+
+ Parameters
+ ----------
+ side : str
+ The border side to expand into properties
+
+ Returns
+ -------
+ function: Return to call when a 'border(-{side}): {value}' string is encountered
+ """
+ if side != "":
+ side = f"-{side}"
+
+ def expand(self, prop, value: str) -> tuple[str, str]:
+ """
+ Expand border into color, style, and width tuples
+
+ Parameters
+ ----------
+ prop : str
+ CSS property name passed to styler
+ value : str
+ Value passed to styler for property
+
+ Yields
+ ------
+ Tuple (str, str): Expanded property, value
+ """
+ tokens = value.split()
+ if len(tokens) == 0 or len(tokens) > 3:
+ warnings.warn(
+ f'Too many tokens provided to "{prop}" (expected 1-3)', CSSWarning
+ )
+
+ # TODO: Can we use current color as initial value to comply with CSS standards?
+ border_declarations = {
+ f"border{side}-color": "black",
+ f"border{side}-style": "none",
+ f"border{side}-width": "medium",
+ }
+ for token in tokens:
+ if token in self.BORDER_STYLES:
+ border_declarations[f"border{side}-style"] = token
+ elif any([ratio in token for ratio in self.BORDER_WIDTH_RATIOS]):
+ border_declarations[f"border{side}-width"] = token
+ else:
+ border_declarations[f"border{side}-color"] = token
+ # TODO: Warn user if item entered more than once (e.g. "border: red green")
+
+ # Per CSS, "border" will reset previous "border-*" definitions
+ yield from self.atomize(border_declarations.items())
+
+ return expand
+
+
 class CSSResolver:
  """
  A callable for parsing and resolving CSS to atomic properties.
  """
 
  UNIT_RATIOS = {
+ "pt": ("pt", 1),
+ "em": ("em", 1),
  "rem": ("pt", 12),
  "ex": ("em", 0.5),
  # 'ch':
@@ -76,6 +165,19 @@ class CSSResolver:
  }
  )
 
+ BORDER_STYLES = [
+ "none",
+ "hidden",
+ "dotted",
+ "dashed",
+ "solid",
+ "double",
+ "groove",
+ "ridge",
+ "inset",
+ "outset",
+ ]
+
  SIDE_SHORTHANDS = {
  1: [0, 0, 0, 0],
  2: [0, 1, 0, 1],
@@ -255,6 +357,12 @@ def atomize(self, declarations):
  for prop, value in expand(prop, value):
  yield prop, value
 
+ expand_border = _border_expander()
+ expand_border_top = _border_expander("top")
+ expand_border_right = _border_expander("right")
+ expand_border_bottom = _border_expander("bottom")
+ expand_border_left = _border_expander("left")
+
  expand_border_color = _side_expander("border-{:s}-color")
  expand_border_style = _side_expander("border-{:s}-style")
  expand_border_width = _side_expander("border-{:s}-width")

pandas/io/formats/excel.py

@@ -235,13 +235,14 @@ def build_border(
  "style": self._border_style(
  props.get(f"border-{side}-style"),
  props.get(f"border-{side}-width"),
+ self.color_to_excel(props.get(f"border-{side}-color")),
  ),
  "color": self.color_to_excel(props.get(f"border-{side}-color")),
  }
  for side in ["top", "right", "bottom", "left"]
  }
 
- def _border_style(self, style: str | None, width: str | None):
+ def _border_style(self, style: str | None, width: str | None, color: str | None):
  # convert styles and widths to openxml, one of:
  # 'dashDot'
  # 'dashDotDot'
@@ -256,14 +257,20 @@ def _border_style(self, style: str | None, width: str | None):
  # 'slantDashDot'
  # 'thick'
  # 'thin'
- if width is None and style is None:
+ if width is None and style is None and color is None:
+ # Return None will remove "border" from style dictionary
  return None
+
+ if width is None and style is None:
+ # Return "none" will keep "border" in style dictionary
+ return "none"
+
  if style == "none" or style == "hidden":
- return None
+ return "none"
 
  width_name = self._get_width_name(width)
  if width_name is None:
- return None
+ return "none"
 
  if style in (None, "groove", "ridge", "inset", "outset", "solid"):
  # not handled

pandas/tests/io/excel/test_style.py

@@ -68,6 +68,44 @@ def test_styler_to_excel_unstyled(engine):
  ["alignment", "vertical"],
  {"xlsxwriter": None, "openpyxl": "bottom"}, # xlsxwriter Fails
  ),
+ # Border widths
+ ("border-left: 2pt solid red", ["border", "left", "style"], "medium"),
+ ("border-left: 1pt dotted red", ["border", "left", "style"], "dotted"),
+ ("border-left: 2pt dotted red", ["border", "left", "style"], "mediumDashDotDot"),
+ ("border-left: 1pt dashed red", ["border", "left", "style"], "dashed"),
+ ("border-left: 2pt dashed red", ["border", "left", "style"], "mediumDashed"),
+ ("border-left: 1pt solid red", ["border", "left", "style"], "thin"),
+ ("border-left: 3pt solid red", ["border", "left", "style"], "thick"),
+ # Border expansion
+ (
+ "border-left: 2pt solid #111222",
+ ["border", "left", "color", "rgb"],
+ {"xlsxwriter": "FF111222", "openpyxl": "00111222"},
+ ),
+ ("border: 1pt solid red", ["border", "top", "style"], "thin"),
+ (
+ "border: 1pt solid #111222",
+ ["border", "top", "color", "rgb"],
+ {"xlsxwriter": "FF111222", "openpyxl": "00111222"},
+ ),
+ ("border: 1pt solid red", ["border", "right", "style"], "thin"),
+ (
+ "border: 1pt solid #111222",
+ ["border", "right", "color", "rgb"],
+ {"xlsxwriter": "FF111222", "openpyxl": "00111222"},
+ ),
+ ("border: 1pt solid red", ["border", "bottom", "style"], "thin"),
+ (
+ "border: 1pt solid #111222",
+ ["border", "bottom", "color", "rgb"],
+ {"xlsxwriter": "FF111222", "openpyxl": "00111222"},
+ ),
+ ("border: 1pt solid red", ["border", "left", "style"], "thin"),
+ (
+ "border: 1pt solid #111222",
+ ["border", "left", "color", "rgb"],
+ {"xlsxwriter": "FF111222", "openpyxl": "00111222"},
+ ),
 ]
 
 
@@ -93,7 +131,7 @@ def test_styler_to_excel_basic(engine, css, attrs, expected):
  # test styled cell has expected styles
  u_cell, s_cell = wb["dataframe"].cell(2, 2), wb["styled"].cell(2, 2)
  for attr in attrs:
- u_cell, s_cell = getattr(u_cell, attr), getattr(s_cell, attr)
+ u_cell, s_cell = getattr(u_cell, attr, None), getattr(s_cell, attr)
 
  if isinstance(expected, dict):
  assert u_cell is None or u_cell != expected[engine]
@@ -134,8 +172,8 @@ def test_styler_to_excel_basic_indexes(engine, css, attrs, expected):
  ui_cell, si_cell = wb["null_styled"].cell(2, 1), wb["styled"].cell(2, 1)
  uc_cell, sc_cell = wb["null_styled"].cell(1, 2), wb["styled"].cell(1, 2)
  for attr in attrs:
- ui_cell, si_cell = getattr(ui_cell, attr), getattr(si_cell, attr)
- uc_cell, sc_cell = getattr(uc_cell, attr), getattr(sc_cell, attr)
+ ui_cell, si_cell = getattr(ui_cell, attr, None), getattr(si_cell, attr)
+ uc_cell, sc_cell = getattr(uc_cell, attr, None), getattr(sc_cell, attr)
 
  if isinstance(expected, dict):
  assert ui_cell is None or ui_cell != expected[engine]

pandas/tests/io/formats/test_css.py

@@ -57,6 +57,8 @@ def test_css_parse_normalisation(name, norm, abnorm):
  ("font-size: 1unknownunit", "font-size: 1em"),
  ("font-size: 10", "font-size: 1em"),
  ("font-size: 10 pt", "font-size: 1em"),
+ # Too many args
+ ("border-top: 1pt solid red green", "border-top: 1pt solid green"),
  ],
 )
 def test_css_parse_invalid(invalid_css, remainder):
@@ -123,6 +125,65 @@ def test_css_side_shorthands(shorthand, expansions):
  assert_resolves(f"{shorthand}: 1pt 1pt 1pt 1pt 1pt", {})
 
 
+@pytest.mark.parametrize(
+ "shorthand,sides",
+ [
+ ("border-top", ["top"]),
+ ("border-right", ["right"]),
+ ("border-bottom", ["bottom"]),
+ ("border-left", ["left"]),
+ ("border", ["top", "right", "bottom", "left"]),
+ ],
+)
+def test_css_border_shorthands(shorthand, sides):
+ def create_border_dict(sides, color=None, style=None, width=None):
+ resolved = {}
+ for side in sides:
+ if color:
+ resolved[f"border-{side}-color"] = color
+ if style:
+ resolved[f"border-{side}-style"] = style
+ if width:
+ resolved[f"border-{side}-width"] = width
+ return resolved
+
+ assert_resolves(
+ f"{shorthand}: 1pt red solid", create_border_dict(sides, "red", "solid", "1pt")
+ )
+
+
+@pytest.mark.parametrize(
+ "prop, expected",
+ [
+ ("1pt red solid", ("red", "solid", "1pt")),
+ ("red 1pt solid", ("red", "solid", "1pt")),
+ ("red solid 1pt", ("red", "solid", "1pt")),
+ ("solid 1pt red", ("red", "solid", "1pt")),
+ ("red solid", ("red", "solid", "1.500000pt")),
+ # Note: color=black is not CSS conforming
+ # (See https://drafts.csswg.org/css-backgrounds/#border-shorthands)
+ ("1pt solid", ("black", "solid", "1pt")),
+ ("1pt red", ("red", "none", "1pt")),
+ ("red", ("red", "none", "1.500000pt")),
+ ("1pt", ("black", "none", "1pt")),
+ ("solid", ("black", "solid", "1.500000pt")),
+ # Sizes
+ ("1em", ("black", "none", "12pt")),
+ ],
+)
+def test_css_border_shorthands(prop, expected):
+ color, style, width = expected
+
+ assert_resolves(
+ f"border-left: {prop}",
+ {
+ "border-left-color": color,
+ "border-left-style": style,
+ "border-left-width": width,
+ },
+ )
+
+
 @pytest.mark.parametrize(
  "style,inherited,equiv",
  [

pandas/tests/io/formats/test_to_excel.py

@@ -187,6 +187,10 @@
  "border-top-style: solid; border-top-color: #06c",
  {"border": {"top": {"style": "medium", "color": "0066CC"}}},
  ),
+ (
+ "border-top-color: blue",
+ {"border": {"top": {"color": "0000FF", "style": "none"}}},
+ ),
  # ALIGNMENT
  # - horizontal
  ("text-align: center", {"alignment": {"horizontal": "center"}}),
@@ -288,7 +292,8 @@ def test_css_to_excel_good_colors(input_color, output_color):
  expected["font"] = {"color": output_color}
 
  expected["border"] = {
- k: {"color": output_color} for k in ("top", "right", "bottom", "left")
+ k: {"color": output_color, "style": "none"}
+ for k in ("top", "right", "bottom", "left")
  }
 
  with tm.assert_produces_warning(None):