Merge remote-tracking branch 'upstream/main' into fix-timeline-daylight-saving

# Conflicts:
#	CHANGELOG.md

Author: mottopanikeiku

CHANGELOG.md

@@ -5,10 +5,15 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## Unreleased
 
 ### Fixed
-- Fix `px.timeline` bars ending an hour early or late when timezone-aware dates span a daylight saving time change [[#4611](https://github.com/plotly/plotly.py/issues/4611)]
+- Fix `mpl_to_plotly` tick marker mirroring, axis positioning, and trace visibility for twinned and overlaid subplots (such as `twinx` and `twiny`) [[#5310](https://github.com/plotly/plotly.py/pull/5310)], with thanks to @robertoffmoura for the contribution!
 - 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!
+- Fix `mpl_to_plotly` drawing step plots with diagonal lines instead of vertical/horizontal step segments by mapping matplotlib step drawstyles (`steps-pre`, `steps-post`, `steps-mid`) to plotly line shapes [[#5697](https://github.com/plotly/plotly.py/pull/5697)], 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!
+- 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!
+- Fix `px.timeline` bars ending an hour early or late when timezone-aware dates span a daylight saving time change [[#5796](https://github.com/plotly/plotly.py/pull/5796)], with thanks to @mottopanikeiku for the contribution!
 
 ## [7.1.0] - 2026-09-15
 

plotly/matplotlylib/mplexporter/utils.py

@@ -200,18 +200,36 @@ def get_text_style(text):
 def get_axis_properties(axis):
     """Return the property dictionary for a matplotlib.Axis instance"""
     props = {}
-    label1On = axis.get_tick_params().get("label1On", True)
+    tick_params = axis.get_tick_params()
 
     if isinstance(axis, matplotlib.axis.XAxis):
-        if label1On:
-            props["position"] = "bottom"
-        else:
+        if (
+            axis.get_ticks_position() == "top"
+            or axis.get_label_position() == "top"
+            or (
+                tick_params.get("labeltop", False)
+                and not tick_params.get("labelbottom", False)
+            )
+            or (tick_params.get("top", False) and not tick_params.get("bottom", False))
+            or not tick_params.get("label1On", True)
+        ):
             props["position"] = "top"
-    elif isinstance(axis, matplotlib.axis.YAxis):
-        if label1On:
-            props["position"] = "left"
         else:
+            props["position"] = "bottom"
+    elif isinstance(axis, matplotlib.axis.YAxis):
+        if (
+            axis.get_ticks_position() == "right"
+            or axis.get_label_position() == "right"
+            or (
+                tick_params.get("labelright", False)
+                and not tick_params.get("labelleft", False)
+            )
+            or (tick_params.get("right", False) and not tick_params.get("left", False))
+            or not tick_params.get("label1On", True)
+        ):
             props["position"] = "right"
+        else:
+            props["position"] = "left"
     else:
         raise ValueError("{0} should be an Axis instance".format(axis))
 
@@ -239,12 +257,15 @@ 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

@@ -12,6 +12,8 @@
 
 from _plotly_utils.colors import hex_to_rgb
 
+from plotly.matplotlylib.mplexporter.utils import export_color
+
 
 def check_bar_match(old_bar, new_bar):
     """Check if two bars belong in the same collection (bar chart).
@@ -106,26 +108,6 @@ def convert_symbol(mpl_symbol):
         return "circle"  # default
 
 
-def merge_color_and_opacity(color, opacity):
-    """
-    Merge hex color with an alpha (opacity) to get an rgba tuple.
-
-    :param (str|unicode) color: A hex color string.
-    :param (float|int) opacity: A value [0, 1] for the 'a' in 'rgba'.
-    :return: (int, int, int, float) The rgba color and alpha tuple.
-
-    """
-    if color is None:  # None can be used as a placeholder, just bail.
-        return None
-
-    rgb_tup = hex_to_rgb(color)
-    if opacity is None:
-        return "rgb{}".format(rgb_tup)
-
-    rgba_tup = rgb_tup + (opacity,)
-    return "rgba{}".format(rgba_tup)
-
-
 def convert_va(mpl_va):
     """Convert mpl vertical alignment word to equivalent HTML word.
 
@@ -250,15 +232,12 @@ def get_axes_bounds(fig):
     return (x_min, x_max), (y_min, y_max)
 
 
-def get_axis_mirror(main_spine, mirror_spine):
-    if main_spine and mirror_spine:
+def get_axis_mirror(main_spine, mirror_spine, main_tick_markers, mirror_tick_markers):
+    if main_spine and mirror_spine and main_tick_markers and mirror_tick_markers:
         return "ticks"
-    elif main_spine and not mirror_spine:
-        return False
-    elif not main_spine and mirror_spine:
-        return False  # can't handle this case yet!
-    else:
-        return False  # nuttin'!
+    if main_spine and mirror_spine:
+        return True
+    return False
 
 
 def get_bar_gap(bar_starts, bar_ends, tol=1e-10):
@@ -278,6 +257,23 @@ def get_bar_gap(bar_starts, bar_ends, tol=1e-10):
             return min(max(gap0 / bar_delta, 0.0), 1.0)
 
 
+DRAWSTYLE_SHAPE_MAP = {
+    "steps": "vh",
+    "steps-pre": "vh",
+    "steps-post": "hv",
+    "steps-mid": "hvh",
+}
+
+
+def convert_drawstyle(drawstyle):
+    """Convert a matplotlib line drawstyle to a plotly line shape.
+
+    Matplotlib draws steps as vertical/horizontal segments; plotly's
+    ``line.shape`` expresses the same via "vh", "hv" and "hvh".
+    """
+    return DRAWSTYLE_SHAPE_MAP.get(drawstyle)
+
+
 def convert_rgba_array(color_list):
     clean_color_list = list()
     for c in color_list:
@@ -516,14 +512,42 @@ def prep_ticks(ax, index, ax_type, props):
     return axis_dict
 
 
+def _export_color(color, opacity=None):
+    """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) keep the alpha
+    they carry unless an explicit opacity overrides it.
+    """
+    if color is None:
+        return None
+    if isinstance(color, (list, tuple)) and all(isinstance(c, str) for c in color):
+        return [_export_color(c, opacity) for c in color]
+    if not isinstance(color, str):
+        color = export_color(color)
+    if color == "none":
+        return "rgba(0,0,0,0)"
+    if color.startswith("#") and opacity is not None:
+        return "rgba{0}".format(hex_to_rgb(color) + (opacity,))
+    if color.startswith("rgb") and opacity not in (None, 1):
+        rgb = color[color.index("(") + 1 : color.rindex(")")].split(",")
+        r, g, b = (int(round(float(component))) for component in rgb[:3])
+        return "rgba({0}, {1}, {2}, {3})".format(r, g, b, opacity)
+    return 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 +556,10 @@ 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