Merge pull request #5716 from robertoffmoura/rm/export-tick-label-color

Export tick label colors to the plotly tickfont

Author: camdecoster

CHANGELOG.md

@@ -7,6 +7,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Fixed
 - Fix concurrent first access to lazily initialized graph object properties, which could raise `ValueError("Invalid value")` [[#5691](https://github.com/plotly/plotly.py/pull/5691)], with thanks to @hb1915 for the contribution!
 - Fix `mpl_to_plotly` crashing on touching bars (such as `plt.hist`) due to floating-point noise producing negative `bargap` values by clamping `bargap` to `[0, 1]` [[#5696](https://github.com/plotly/plotly.py/pull/5696)], with thanks to @robertoffmoura 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 `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!
 
 ## [7.1.0] - 2026-09-15

plotly/matplotlylib/mplexporter/utils.py

@@ -239,12 +239,15 @@ def get_axis_properties(axis):
     # Get axis scale
     props["scale"] = axis.get_scale()
 
-    # Get major tick label size (assumes that's all we really care about!)
+    # Get major tick label size and color (assumes that's all we really
+    # care about!)
     labels = axis.get_ticklabels()
     if labels:
         props["fontsize"] = labels[0].get_fontsize()
+        props["fontcolor"] = export_color(labels[0].get_color())
     else:
         props["fontsize"] = None
+        props["fontcolor"] = None
 
     # Get associated grid
     props["grid"] = get_grid_style(axis)

plotly/matplotlylib/mpltools.py

@@ -516,14 +516,32 @@ def prep_ticks(ax, index, ax_type, props):
     return axis_dict
 
 
+def _export_color(color):
+    """Export a matplotlib color for use as a plotly color.
+
+    matplotlib uses "none" for fully transparent colors, which plotly does not
+    accept, so transparent colors are exported as transparent black.
+    Colors already exported by the mplexporter (hex or rgba strings) are
+    passed through unchanged.
+    """
+    if color is None:
+        return None
+    if isinstance(color, str):
+        return color if color != "none" else "rgba(0,0,0,0)"
+    return [_export_color(c) for c in color]
+
+
 def prep_xy_axis(ax, props, x_bounds, y_bounds):
     xaxis = dict(
         type=props["axes"][0]["scale"],
         range=list(props["xlim"]),
         showgrid=props["axes"][0]["grid"]["gridOn"],
         domain=convert_x_domain(props["bounds"], x_bounds),
         side=props["axes"][0]["position"],
-        tickfont=dict(size=props["axes"][0]["fontsize"]),
+        tickfont=dict(
+            size=props["axes"][0]["fontsize"],
+            color=_export_color(props["axes"][0]["fontcolor"]),
+        ),
     )
     xaxis.update(prep_ticks(ax, 0, "x", props))
     yaxis = dict(
@@ -532,7 +550,10 @@ def prep_xy_axis(ax, props, x_bounds, y_bounds):
         showgrid=props["axes"][1]["grid"]["gridOn"],
         domain=convert_y_domain(props["bounds"], y_bounds),
         side=props["axes"][1]["position"],
-        tickfont=dict(size=props["axes"][1]["fontsize"]),
+        tickfont=dict(
+            size=props["axes"][1]["fontsize"],
+            color=_export_color(props["axes"][1]["fontcolor"]),
+        ),
     )
     yaxis.update(prep_ticks(ax, 1, "y", props))
     return xaxis, yaxis

plotly/matplotlylib/renderer.py

@@ -14,17 +14,7 @@
 from plotly.matplotlylib import mpltools
 
 
-def _export_color(color):
-    """Export a matplotlib color for use as a plotly color.
-
-    matplotlib uses "none" for fully transparent colors, which plotly does not
-    accept, so transparent colors are exported as transparent black.
-    Colors already exported by the mplexporter (hex or rgba strings) are
-    passed through unchanged.
-    """
-    if isinstance(color, str):
-        return "rgba(0,0,0,0)" if color == "none" else color
-    return [_export_color(c) for c in color]
+from plotly.matplotlylib.mpltools import _export_color
 
 
 class PlotlyRenderer(Renderer):

plotly/matplotlylib/tests/test_renderer.py

@@ -366,3 +366,37 @@ def test_custom_date_xtickvals_given_as_numbers_are_converted():
         "2023-01-07 00:00:00",
         "2023-01-10 00:00:00",
     )
+
+
+def test_tick_label_color_exports():
+    """Tick label colors are exported to the plotly tickfont."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.tickfont.color == "#000000"
+
+
+def test_dark_tick_label_color_exports():
+    """Dark-background tick label colors are exported to the plotly
+    tickfont."""
+    with plt.style.context("dark_background"):
+        fig, ax = plt.subplots()
+        ax.plot([0, 1], [0, 1])
+
+        plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.tickfont.color == "#FFFFFF"
+
+
+def test_transparent_tick_label_color_exports():
+    """Transparent tick label colors ('none') export as transparent rgba."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+    ax.tick_params(labelcolor="none")
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.tickfont.color == "rgba(0,0,0,0)"
+    assert plotly_fig.layout.yaxis.tickfont.color == "rgba(0,0,0,0)"