more complete *mode support

Author: nicolaskruchten

gallery.md

@@ -5,7 +5,7 @@ jupyter:
     text_representation:
       extension: .md
       format_name: markdown
-      format_version: "1.1"
+      format_version: '1.1'
       jupytext_version: 1.1.1
   kernelspec:
     display_name: Python 3

plotly_express/_chart_types.py

@@ -267,6 +267,7 @@ def violin(
     color_discrete_sequence=default_qualitative,
     color_discrete_map={},
     orientation="v",
+    violinmode="group",
     log_x=False,
     log_y=False,
     range_x=None,
@@ -290,8 +291,10 @@ def violin(
             points=points,
             box=dict(visible=box),
             scalegroup=True,
+            x0=" ",
+            y0=" ",
         ),
-        layout_patch=dict(violinmode="group"),
+        layout_patch=dict(violinmode=violinmode),
     )
 
 
@@ -314,6 +317,7 @@ def box(
     color_discrete_sequence=default_qualitative,
     color_discrete_map={},
     orientation="v",
+    boxmode="group",
     log_x=False,
     log_y=False,
     range_x=None,
@@ -332,8 +336,10 @@ def box(
     return make_figure(
         args=locals(),
         constructor=go.Box,
-        trace_patch=dict(orientation=orientation, boxpoints=points, notched=notched),
-        layout_patch=dict(boxmode="group"),
+        trace_patch=dict(
+            orientation=orientation, boxpoints=points, notched=notched, x0=" ", y0=" "
+        ),
+        layout_patch=dict(boxmode=boxmode),
     )
 
 

plotly_express/_core.py

@@ -286,8 +286,6 @@ def configure_cartesian_marginal_axes(args, orders):
     layout = dict()
     if "histogram" in [args["marginal_x"], args["marginal_y"]]:
         layout["barmode"] = "overlay"
-    if "violin" in [args["marginal_x"], args["marginal_y"]]:
-        layout["violinmode"] = "overlay"
     for letter in ["x", "y"]:
         layout[letter + "axis1"] = dict(
             title=get_decorated_label(args, args[letter], letter)
@@ -628,7 +626,11 @@ def infer_config(args, constructor, trace_patch):
 
     trace_patch = trace_patch.copy()
     if "opacity" in args:
-        trace_patch["marker"] = dict(opacity=args["opacity"])
+        if args["opacity"] is None:
+            if "barmode" in args and args["barmode"] == "overlay":
+                trace_patch["marker"] = dict(opacity=0.5)
+        else:
+            trace_patch["marker"] = dict(opacity=args["opacity"])
     if "line_group" in args:
         trace_patch["mode"] = "lines" + ("+markers+text" if args["text"] else "")
     elif constructor != go.Splom and (

plotly_express/_doc.py

@@ -268,10 +268,21 @@
         "`'percent'` is the same but multiplied by 100 to show percentages.",
     ],
     barmode=[
-        "(string, one of `'group'` or `'relative'`. Default is `'relative'`)",
+        "(string, one of `'group'`, `'overlay'` or `'relative'`. Default is `'relative'`)",
         "In `'relative'` mode, bars are stacked above zero for positive values and below zero for negative values.",
+        "In `'overlay'` mode, bars are on drawn top of one another.",
         "In `'group'` mode, bars are placed beside each other.",
     ],
+    boxmode=[
+        "(string, one of `'group'` or `'overlay'`. Default is `'group'`)",
+        "In `'overlay'` mode, boxes are on drawn top of one another.",
+        "In `'group'` mode, baxes are placed beside each other.",
+    ],
+    violinmode=[
+        "(string, one of `'group'` or `'overlay'`. Default is `'group'`)",
+        "In `'overlay'` mode, violins are on drawn top of one another.",
+        "In `'group'` mode, violins are placed beside each other.",
+    ],
     zoom=["(integer between 0 and 20, default is 8)", "Sets map zoom level."],
     orientation=["(string, one of `'h'` or `'v'`)", "Default is `'v'`."],
     line_close=[