CODEWITHSUNDEEP
pythonbokeh
petezurich
petezurich

Reputation: 10184

How to set the legend color's transparency in Bokeh independently from fill_alpha of scatter plot?

For a complex scatterplot with 20k+ points I need to set the fill_alpha of the scatter points to a low value, say 0.2.

How can I set the fill color in the legend to full opaque (aka not transparent)?

enter image description here

Example code:

from bokeh.plotting import figure, output_file, show
from bokeh.models import ColumnDataSource

p = figure(plot_width=640, plot_height=320)

x = [10]
y = [10]
color = ["blue"]
category = ["Lorem Ipsum"]

source = ColumnDataSource(dict(x = x, y = y, color=color, legsrc=category))

p.scatter(x="x", y="x", fill_alpha=.2, size=100, color="color",
         line_color=None, marker="circle", source=source, legend="legsrc")

show(p)

Upvotes: 3

Views: 1969

Answers (2)

Fra
Fra

Reputation: 11

For sure I'm out of time, but maybe could still help others. I solved this by making two different plots: the first with color mapping and no legend, the second with a single color, with legend option and size=0 (so it is not displayed)

In your case:

p.scatter(x="x", y="x", fill_alpha=.2, size=100, color="color",
         line_color=None, marker="circle", source=source)

p.scatter(x="x", y="x", size=0, color="lightgrey",
         line_color=None, marker="circle", source=source, legend="legsrc")

Upvotes: 1

bigreddot
bigreddot

Reputation: 34568

As of Bokeh 1.0.2. this is not possible. Legend items always mirror the visual properties of the glyph they represent exactly, including alpha. If you would like to discuss the possibility of adding some mechanism to override legend glyph properties, the next step would be to make a detailed feature request issue on GitHub.

Upvotes: 1

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