Convert matplotlib step drawstyles to plotly line shapes

Author: robertoffmoura

plotly/matplotlylib/mpltools.py

@@ -272,6 +272,23 @@ def get_bar_gap(bar_starts, bar_ends, tol=1e-10):
             return gap0
 
 
+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:

plotly/matplotlylib/renderer.py

@@ -404,6 +404,9 @@ def draw_marked_line(self, **props):
                     color=color,
                     width=props["linestyle"]["linewidth"],
                     dash=mpltools.convert_dash(props["linestyle"]["dasharray"]),
+                    shape=mpltools.convert_drawstyle(
+                        props["linestyle"]["drawstyle"]
+                    ),
                 )
             else:
                 shape = dict(

plotly/matplotlylib/tests/test_renderer.py

@@ -199,3 +199,17 @@ def test_filled_path_collection_date_xaxis():
     filled = [t for t in plotly_fig.data if t.fill == "toself"]
     assert len(filled) >= 1
     assert all(isinstance(x, str) for x in filled[0].x)
+
+
+def test_drawstyle_maps_to_line_shape():
+    cases = {
+        "steps-pre": "vh",
+        "steps": "vh",
+        "steps-post": "hv",
+        "steps-mid": "hvh",
+    }
+    for drawstyle, shape in cases.items():
+        fig, ax = plt.subplots()
+        ax.plot([0, 1, 2], [0, 1, 0], drawstyle=drawstyle)
+        plotly_fig = tls.mpl_to_plotly(fig)
+        assert plotly_fig.data[0].line.shape == shape