Fix validate_colors and convert_colors_to_same_type modifying the colors passed to them

CHANGELOG.md

@@ -16,13 +16,15 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Fix `mpl_to_plotly` dropping matplotlib stairs plots by rendering `StepPatch` artists as step lines or filled step areas from their path vertices and edge style [[#5698](https://github.com/plotly/plotly.py/pull/5698)], with thanks to @robertoffmoura for the contribution!
 - Fix `mpl_to_plotly` showing unwanted legends with placeholder or internal label entries (`_nolegend_`, `_childN`) by defaulting `layout.showlegend=False` unless the matplotlib figure explicitly defines a legend [[#5699](https://github.com/plotly/plotly.py/pull/5699)], with thanks to @robertoffmoura for the contribution!
 - Fix `mpl_to_plotly` crashing on figures with fully transparent or alpha-carrying colors, such as boxplot outlier markers (`facecolor="none"`), rgba line colors, and `color="none"` text and axis labels; all matplotlib colors are now exported through a single helper that maps `"none"` to transparent rgba and keeps or overrides alpha as matplotlib does [[#5700](https://github.com/plotly/plotly.py/pull/5700)], with thanks to @robertoffmoura for the contribution!
+- Fix serialization of box/lasso select data for figures with multiple subplots [[#5710](https://github.com/plotly/plotly.py/pull/5710)], with thanks to @flpi-sun for the contribution!
 - Export tick label colors to the plotly tickfont in `mpl_to_plotly` [[#5716](https://github.com/plotly/plotly.py/pull/5716)], with thanks to @robertoffmoura for the contribution!
-- Fix Plotly Express mutating lists passed to the `x` or `y` arguments in wide mode [[#5727](https://github.com/plotly/plotly.py/pull/5727)], with thanks to @cpruijsen for the contribution!
 - Fix `convert_dash` mapping dotted lines (`linestyle=':'`) to invalid `'circle'` in Plotly, correctly converting them to `'dot'` and preserving custom dash patterns as pixel lists, [[#5719](https://github.com/plotly/plotly.py/pull/5719)] with thanks to @robertoffmoura for the contribution!
+- Fix Plotly Express mutating lists passed to the `x` or `y` arguments in wide mode [[#5727](https://github.com/plotly/plotly.py/pull/5727)], with thanks to @cpruijsen for the contribution!
 - Fix `px.sunburst`, `px.treemap` and `px.icicle` listing sectors in a different order on every run when `path` is used with a Polars DataFrame; sectors now follow their order of first appearance for all dataframe backends [[#5766](https://github.com/plotly/plotly.py/pull/5766)], with thanks to @Irahan2 for the contribution!
 - Fix `mpl_to_plotly` conversion of matplotlib contour lines and line collections: close contour rings ending with `Z` codes, support dash styles, convert date x-axes, separate disjoint subpaths with `None` separators, hide line collection traces from the legend by default, and group consecutive same-style lines into single traces [[#5770](https://github.com/plotly/plotly.py/pull/5770)], with thanks to @robertoffmoura for the contribution!
-- Fix serialization of box/lasso select data for figures with multiple subplots [[#5710](https://github.com/plotly/plotly.py/pull/5710)], with thanks to @flpi-sun for the contribution!
 - Fix `plotly.io.write_images` ignoring `layout.width`/`layout.height` (and the template's) and exporting every figure at the default 700x500 size; it now uses the same width/height priority as `write_image` and `to_image` [[#5784](https://github.com/plotly/plotly.py/pull/5784)], with thanks to @breken-ai for the contribution!
+- Fix color utilities mutating the list of colors passed to them [[#5836](https://github.com/plotly/plotly.py/pull/5836)], with thanks to @Enesuygurs for the contribution!
+
 
 ## [7.1.0] - 2026-09-15
 

_plotly_utils/colors/__init__.py

@@ -338,6 +338,11 @@ def validate_colors(colors, colortype="tuple"):
         else:
             colors = list(colors)
 
+    else:
+        # copy the list so that neither the caller's list nor
+        # DEFAULT_PLOTLY_COLORS is modified in place below
+        colors = list(colors)
+
     # convert color elements in list to tuple color
     for j, each_color in enumerate(colors):
         if "rgb" in each_color:
@@ -377,6 +382,9 @@ def validate_colors_dict(colors, colortype="tuple"):
     """
     Validates dictionary of color(s)
     """
+    # copy the dict so that the caller's dict is not modified in place below
+    colors = dict(colors)
+
     # validate each color element in the dictionary
     for key in colors:
         if "rgb" in colors[key]:
@@ -454,7 +462,7 @@ def convert_colors_to_same_type(
             colors_list = list(colors)
 
     elif isinstance(colors, list):
-        colors_list = colors
+        colors_list = list(colors)
 
     # validate scale
     if scale is not None:
@@ -498,6 +506,9 @@ def convert_dict_colors_to_same_type(colors_dict, colortype="rgb"):
 
     :param (dict) colors_dict: a dictionary whose values are single colors
     """
+    # copy the dict so that the caller's dict is not modified in place below
+    colors_dict = dict(colors_dict)
+
     for key in colors_dict:
         if "#" in colors_dict[key]:
             colors_dict[key] = color_parser(colors_dict[key], hex_to_rgb)
@@ -818,6 +829,10 @@ def convert_colorscale_to_rgb(colorscale):
     converting a colorscale with tuple colors (each coordinate between 0
     and 1) into a colorscale with the colors transformed into rgb colors
     """
+    # copy the colorscale and its [scale, color] pairs so that the caller's
+    # colorscale is not modified in place below
+    colorscale = [list(color) for color in colorscale]
+
     for color in colorscale:
         color[1] = convert_to_RGB_255(color[1])
 

tests/test_core/test_colors/test_colors.py

@@ -59,6 +59,32 @@ def test_convert_colors_to_same_type(self):
             colortype,
         )
 
+    def test_color_conversions_do_not_modify_input(self):
+        default_colors = list(colors.DEFAULT_PLOTLY_COLORS)
+
+        colors.validate_colors(None)
+        self.assertEqual(colors.DEFAULT_PLOTLY_COLORS, default_colors)
+
+        color_list = ["rgb(255, 0, 0)", "#0000ff"]
+        colors.validate_colors(color_list)
+        self.assertEqual(color_list, ["rgb(255, 0, 0)", "#0000ff"])
+
+        colors.convert_colors_to_same_type(color_list, colortype="tuple")
+        self.assertEqual(color_list, ["rgb(255, 0, 0)", "#0000ff"])
+
+        color_dict = {"a": "rgb(255, 0, 0)", "b": "#0000ff", "c": (0.5, 0.5, 0.5)}
+        expected_dict = dict(color_dict)
+
+        colors.validate_colors_dict(color_dict, colortype="rgb")
+        self.assertEqual(color_dict, expected_dict)
+
+        colors.convert_dict_colors_to_same_type(color_dict, colortype="tuple")
+        self.assertEqual(color_dict, expected_dict)
+
+        colorscale = [[0, (0.0, 0.0, 0.0)], [1, (1.0, 1.0, 1.0)]]
+        colors.convert_colorscale_to_rgb(colorscale)
+        self.assertEqual(colorscale, [[0, (0.0, 0.0, 0.0)], [1, (1.0, 1.0, 1.0)]])
+
     def test_convert_dict_colors_to_same_type(self):
         # test colortype
         color_dict = dict(apple="rgb(1, 1, 1)")