Fix y-axis showline and hide tick markers when mpl ticks are hidden

Author: robertoffmoura

plotly/matplotlylib/renderer.py

@@ -197,7 +197,12 @@ def open_axes(self, ax, props):
             left_spine, right_spine, left_tick_markers, right_tick_markers
         )
         xaxis["showline"] = bottom_spine
-        yaxis["showline"] = top_spine
+        yaxis["showline"] = left_spine
+        # hide tick markers when the mpl main-side tick markers are hidden
+        if not bottom_tick_markers:
+            xaxis["ticks"] = ""
+        if not left_tick_markers:
+            yaxis["ticks"] = ""
 
         # put axes in our figure
         self.plotly_fig["layout"]["xaxis{0}".format(self.axis_ct)] = xaxis

plotly/matplotlylib/tests/test_renderer.py

@@ -89,7 +89,6 @@ def test_multiple_traces_native_legend():
     assert plotly_fig.data[2].mode == "lines+markers"
 
 
-
 def test_axis_mirror_with_spines_and_ticks():
     """Test that mirror=True when both spines and ticks are visible on both sides."""
     fig, ax = plt.subplots()
@@ -164,6 +163,49 @@ def test_axis_mirror_mixed_configurations():
     assert plotly_fig.layout.yaxis.mirror == False
 
 
+def test_axis_showline_tied_to_main_spine():
+    """Test that showline follows the main-side spine (bottom for x, left for y)."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+
+    # Hide the mirror-side spines only
+    ax.spines["top"].set_visible(False)
+    ax.spines["right"].set_visible(False)
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.showline == True
+    assert plotly_fig.layout.yaxis.showline == True
+
+
+def test_axis_showline_hidden_when_main_spine_hidden():
+    """Test that showline is False when the main-side spine is hidden."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+
+    # Hide the main-side spines but keep the mirror-side ones
+    ax.spines["bottom"].set_visible(False)
+    ax.spines["left"].set_visible(False)
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.showline == False
+    assert plotly_fig.layout.yaxis.showline == False
+
+
+def test_ticks_hidden_when_mpl_main_ticks_hidden():
+    """Test that tick markers are hidden when the mpl main-side ticks are hidden."""
+    fig, ax = plt.subplots()
+    ax.plot([0, 1], [0, 1])
+
+    ax.tick_params(top=False, bottom=False, left=False, right=False)
+
+    plotly_fig = tls.mpl_to_plotly(fig)
+
+    assert plotly_fig.layout.xaxis.ticks == ""
+    assert plotly_fig.layout.yaxis.ticks == ""
+
+
 def test_violinplot_bodies_are_filled_polygons():
     fig, ax = plt.subplots()
     ax.violinplot(np.random.randn(100, 3))