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[Bug] Plotly express color_continuous_scale ignored when template has autocolorscale=True #5433
Description
Problem
When a Plotly template sets coloraxis_autocolorscale=True, the color_continuous_scale argument passed to plotly.express functions is ignored.
Reproduction
import plotly.express as px
import plotly.graph_objects as go
df = px.data.gapminder().query("year == 2007")
template = go.layout.Template(layout=go.Layout(coloraxis_autocolorscale=True))
# User specifies colorscale - THIS IS IGNORED
fig = px.choropleth(
df,
locations="iso_alpha",
color="lifeExp",
color_continuous_scale=["red", "yellow", "green"],
template=template,
)
fig.show() # Renders with auto-detected scale, not red-yellow-greenRoot cause
As per the plotly docs, when autocolorscale=True, the colorscale is auto-detected based on the data, ignoring any explicit colorscale setting (this itself is quite confusing behaviour I think, but that's a separate issue - let's assume for now it should be left with that logic):
In case
colorscaleis unspecified orautocolorscaleis True, the default palette will be chosen according to whether numbers in thecolorarray are all positive, all negative or mixed.
In the following code autocolorscale is not set on coloraxis1. This means the template's autocolorscale=True is inherited, causing the user's color_continuous_scale to be completely ignored:
plotly.py/plotly/express/_core.py
Lines 2707 to 2716 in f083977
Proposed fix
When color_continuous_scale is explicitly provided, set autocolorscale=False on coloraxis1 to ensure the user's colorscale is respected. I can raise a PR for this if you like!
Activity
robertclaus commentedon Nov 26, 2025
Agreed that this isn't the most intuitive behavior. We would be open to making this change if you could open a PR. The only notable concern would be around backwards compatibility if anyone was assuming this behavior.
antonymilne commentedon Dec 2, 2025
Hi @robertclaus, I've opened a PR to fix this in #5439.
I've gone for the "light touch" fix that only affects Plotly Express so there shouldn't be any concerns around backwards compatibility here.
Just to be clear, as I see it the underlying behaviour of plotly.js is quite confusing and unexpected:
i.e. when
autocolorscale=Trueandcolorscaleis specified explicitly,colorscalewill be ignored. To me it really feels like the "or" condition here should be "and", so thatautocolorscaleis only relevant whencolorscaleisn't specified explicitly. I don't know whether this is a bug or intentional.Either way, I decided that for simplicity I would just fix this on the Plotly Express side (where the bug is most obvious and problematic) to ensure there's no backwards compatibility issues.