Backport PR #38247 on branch 1.2.x (BUG: Limited available colors)

doc/source/whatsnew/v1.2.0.rst

@@ -308,6 +308,7 @@ Other enhancements
 - Improved error reporting for subsetting columns of a :class:`.DataFrameGroupBy` with ``axis=1`` (:issue:`37725`)
 - Implement method ``cross`` for :meth:`DataFrame.merge` and :meth:`DataFrame.join` (:issue:`5401`)
 - When :func:`read_csv/sas/json` are called with ``chuncksize``/``iterator`` they can be used in a ``with`` statement as they return context-managers (:issue:`38225`)
+- Augmented the list of named colors available for styling Excel exports, enabling all of CSS4 colors (:issue:`38247`)
 
 .. ---------------------------------------------------------------------------
 

pandas/io/formats/_color_data.py

@@ -0,0 +1,155 @@
+# GH37967: Enable the use of CSS named colors, as defined in
+# matplotlib.colors.CSS4_COLORS, when exporting to Excel.
+# This data has been copied here, instead of being imported from matplotlib,
+# not to have ``to_excel`` methods require matplotlib.
+# source: matplotlib._color_data (3.3.3)
+CSS4_COLORS = {
+    "aliceblue": "F0F8FF",
+    "antiquewhite": "FAEBD7",
+    "aqua": "00FFFF",
+    "aquamarine": "7FFFD4",
+    "azure": "F0FFFF",
+    "beige": "F5F5DC",
+    "bisque": "FFE4C4",
+    "black": "000000",
+    "blanchedalmond": "FFEBCD",
+    "blue": "0000FF",
+    "blueviolet": "8A2BE2",
+    "brown": "A52A2A",
+    "burlywood": "DEB887",
+    "cadetblue": "5F9EA0",
+    "chartreuse": "7FFF00",
+    "chocolate": "D2691E",
+    "coral": "FF7F50",
+    "cornflowerblue": "6495ED",
+    "cornsilk": "FFF8DC",
+    "crimson": "DC143C",
+    "cyan": "00FFFF",
+    "darkblue": "00008B",
+    "darkcyan": "008B8B",
+    "darkgoldenrod": "B8860B",
+    "darkgray": "A9A9A9",
+    "darkgreen": "006400",
+    "darkgrey": "A9A9A9",
+    "darkkhaki": "BDB76B",
+    "darkmagenta": "8B008B",
+    "darkolivegreen": "556B2F",
+    "darkorange": "FF8C00",
+    "darkorchid": "9932CC",
+    "darkred": "8B0000",
+    "darksalmon": "E9967A",
+    "darkseagreen": "8FBC8F",
+    "darkslateblue": "483D8B",
+    "darkslategray": "2F4F4F",
+    "darkslategrey": "2F4F4F",
+    "darkturquoise": "00CED1",
+    "darkviolet": "9400D3",
+    "deeppink": "FF1493",
+    "deepskyblue": "00BFFF",
+    "dimgray": "696969",
+    "dimgrey": "696969",
+    "dodgerblue": "1E90FF",
+    "firebrick": "B22222",
+    "floralwhite": "FFFAF0",
+    "forestgreen": "228B22",
+    "fuchsia": "FF00FF",
+    "gainsboro": "DCDCDC",
+    "ghostwhite": "F8F8FF",
+    "gold": "FFD700",
+    "goldenrod": "DAA520",
+    "gray": "808080",
+    "green": "008000",
+    "greenyellow": "ADFF2F",
+    "grey": "808080",
+    "honeydew": "F0FFF0",
+    "hotpink": "FF69B4",
+    "indianred": "CD5C5C",
+    "indigo": "4B0082",
+    "ivory": "FFFFF0",
+    "khaki": "F0E68C",
+    "lavender": "E6E6FA",
+    "lavenderblush": "FFF0F5",
+    "lawngreen": "7CFC00",
+    "lemonchiffon": "FFFACD",
+    "lightblue": "ADD8E6",
+    "lightcoral": "F08080",
+    "lightcyan": "E0FFFF",
+    "lightgoldenrodyellow": "FAFAD2",
+    "lightgray": "D3D3D3",
+    "lightgreen": "90EE90",
+    "lightgrey": "D3D3D3",
+    "lightpink": "FFB6C1",
+    "lightsalmon": "FFA07A",
+    "lightseagreen": "20B2AA",
+    "lightskyblue": "87CEFA",
+    "lightslategray": "778899",
+    "lightslategrey": "778899",
+    "lightsteelblue": "B0C4DE",
+    "lightyellow": "FFFFE0",
+    "lime": "00FF00",
+    "limegreen": "32CD32",
+    "linen": "FAF0E6",
+    "magenta": "FF00FF",
+    "maroon": "800000",
+    "mediumaquamarine": "66CDAA",
+    "mediumblue": "0000CD",
+    "mediumorchid": "BA55D3",
+    "mediumpurple": "9370DB",
+    "mediumseagreen": "3CB371",
+    "mediumslateblue": "7B68EE",
+    "mediumspringgreen": "00FA9A",
+    "mediumturquoise": "48D1CC",
+    "mediumvioletred": "C71585",
+    "midnightblue": "191970",
+    "mintcream": "F5FFFA",
+    "mistyrose": "FFE4E1",
+    "moccasin": "FFE4B5",
+    "navajowhite": "FFDEAD",
+    "navy": "000080",
+    "oldlace": "FDF5E6",
+    "olive": "808000",
+    "olivedrab": "6B8E23",
+    "orange": "FFA500",
+    "orangered": "FF4500",
+    "orchid": "DA70D6",
+    "palegoldenrod": "EEE8AA",
+    "palegreen": "98FB98",
+    "paleturquoise": "AFEEEE",
+    "palevioletred": "DB7093",
+    "papayawhip": "FFEFD5",
+    "peachpuff": "FFDAB9",
+    "peru": "CD853F",
+    "pink": "FFC0CB",
+    "plum": "DDA0DD",
+    "powderblue": "B0E0E6",
+    "purple": "800080",
+    "rebeccapurple": "663399",
+    "red": "FF0000",
+    "rosybrown": "BC8F8F",
+    "royalblue": "4169E1",
+    "saddlebrown": "8B4513",
+    "salmon": "FA8072",
+    "sandybrown": "F4A460",
+    "seagreen": "2E8B57",
+    "seashell": "FFF5EE",
+    "sienna": "A0522D",
+    "silver": "C0C0C0",
+    "skyblue": "87CEEB",
+    "slateblue": "6A5ACD",
+    "slategray": "708090",
+    "slategrey": "708090",
+    "snow": "FFFAFA",
+    "springgreen": "00FF7F",
+    "steelblue": "4682B4",
+    "tan": "D2B48C",
+    "teal": "008080",
+    "thistle": "D8BFD8",
+    "tomato": "FF6347",
+    "turquoise": "40E0D0",
+    "violet": "EE82EE",
+    "wheat": "F5DEB3",
+    "white": "FFFFFF",
+    "whitesmoke": "F5F5F5",
+    "yellow": "FFFF00",
+    "yellowgreen": "9ACD32",
+}

pandas/io/formats/excel.py

@@ -21,6 +21,7 @@
 from pandas.core import generic
 import pandas.core.common as com
 
+from pandas.io.formats._color_data import CSS4_COLORS
 from pandas.io.formats.css import CSSResolver, CSSWarning
 from pandas.io.formats.format import get_level_lengths
 from pandas.io.formats.printing import pprint_thing
@@ -65,28 +66,7 @@ class CSSToExcelConverter:
         CSS processed by :meth:`__call__`.
     """
 
-    NAMED_COLORS = {
-        "maroon": "800000",
-        "brown": "A52A2A",
-        "red": "FF0000",
-        "pink": "FFC0CB",
-        "orange": "FFA500",
-        "yellow": "FFFF00",
-        "olive": "808000",
-        "green": "008000",
-        "purple": "800080",
-        "fuchsia": "FF00FF",
-        "lime": "00FF00",
-        "teal": "008080",
-        "aqua": "00FFFF",
-        "blue": "0000FF",
-        "navy": "000080",
-        "black": "000000",
-        "gray": "808080",
-        "grey": "808080",
-        "silver": "C0C0C0",
-        "white": "FFFFFF",
-    }
+    NAMED_COLORS = CSS4_COLORS
 
     VERTICAL_MAP = {
         "top": "top",

pandas/tests/io/formats/test_to_excel.py

@@ -2,9 +2,12 @@
 
 ExcelFormatter is tested implicitly in pandas/tests/io/excel
 """
+import string
 
 import pytest
 
+import pandas.util._test_decorators as td
+
 import pandas._testing as tm
 
 from pandas.io.formats.css import CSSWarning
@@ -313,3 +316,18 @@ def test_css_to_excel_bad_colors(input_color):
     with tm.assert_produces_warning(CSSWarning):
         convert = CSSToExcelConverter()
         assert expected == convert(css)
+
+
+def tests_css_named_colors_valid():
+    upper_hexs = set(map(str.upper, string.hexdigits))
+    for color in CSSToExcelConverter.NAMED_COLORS.values():
+        assert len(color) == 6 and all(c in upper_hexs for c in color)
+
+
+@td.skip_if_no_mpl
+def test_css_named_colors_from_mpl_present():
+    from matplotlib.colors import CSS4_COLORS as mpl_colors
+
+    pd_colors = CSSToExcelConverter.NAMED_COLORS
+    for name, color in mpl_colors.items():
+        assert name in pd_colors and pd_colors[name] == color[1:]