range_color, closes #72

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
@@ -223,7 +223,7 @@ px.line_geo(gapminder.query("year==2007"), locations="iso_alpha", color="contine
 
 ```python
 px.choropleth(gapminder, locations="iso_alpha", color="lifeExp", hover_name="country", animation_frame="year",
-             color_continuous_scale=px.colors.sequential.Plasma)
+             color_continuous_scale=px.colors.sequential.Plasma, range_color=[20,80])
 ```
 
 ## Built-in Color Scales and Sequences (and a way to see them!)

plotly_express/_chart_types.py

@@ -26,6 +26,7 @@ def scatter(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     symbol_sequence=None,
     symbol_map={},
@@ -124,6 +125,7 @@ def density_heatmap(
     category_orders={},
     labels={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     marginal_x=None,
     marginal_y=None,
@@ -272,6 +274,7 @@ def bar(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     opacity=None,
     orientation="v",
@@ -527,6 +530,7 @@ def scatter_3d(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     symbol_sequence=None,
     symbol_map={},
@@ -614,6 +618,7 @@ def scatter_ternary(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     symbol_sequence=None,
     symbol_map={},
@@ -684,6 +689,7 @@ def scatter_polar(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     symbol_sequence=None,
     symbol_map={},
@@ -800,6 +806,7 @@ def choropleth(
     category_orders={},
     labels={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     size_max=None,
     projection=None,
@@ -841,6 +848,7 @@ def scatter_geo(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     opacity=None,
     size_max=None,
@@ -922,6 +930,7 @@ def scatter_mapbox(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     opacity=None,
     size_max=None,
@@ -983,6 +992,7 @@ def scatter_matrix(
     color_discrete_sequence=None,
     color_discrete_map={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     symbol_sequence=None,
     symbol_map={},
@@ -1012,6 +1022,7 @@ def parallel_coordinates(
     color=None,
     labels={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     title=None,
     template=None,
@@ -1035,6 +1046,7 @@ def parallel_categories(
     color=None,
     labels={},
     color_continuous_scale=None,
+    range_color=None,
     color_continuous_midpoint=None,
     title=None,
     template=None,

plotly_express/_core.py

@@ -897,17 +897,17 @@ def make_figure(args, constructor, trace_patch={}, layout_patch={}):
         )
     layout_patch = layout_patch.copy()
     if show_colorbar:
-        if "color" in args:
-            colorvar = "color"
-        elif constructor == go.Histogram2d:
-            colorvar = "z"
+        colorvar = "z" if constructor == go.Histogram2d else "color"
+        range_color = args["range_color"] or [None, None]
         d = len(args["color_continuous_scale"]) - 1
         layout_patch["coloraxis1"] = dict(
             colorscale=[
                 [(1.0 * i) / (1.0 * d), x]
                 for i, x in enumerate(args["color_continuous_scale"])
             ],
             cmid=args["color_continuous_midpoint"],
+            cmin=range_color[0],
+            cmax=range_color[1],
             colorbar=dict(title=get_decorated_label(args, args[colorvar], colorvar)),
         )
     for v in ["title", "height", "width", "template"]:

plotly_express/_doc.py

@@ -199,6 +199,10 @@
         "(2-element list of numbers)",
         "If provided, overrides auto-scaling on the z-axis in cartesian coordinates.",
     ],
+    range_color=[
+        "(2-element list of numbers)",
+        "If provided, overrides auto-scaling on the continuous color scale.",
+    ],
     range_r=[
         "(2-element list of numbers)",
         "If provided, overrides auto-scaling on the radial axis in polar coordinates.",