How to add legend inside Python's Bokeh circle plot

Question

I have the following code:

from bokeh.plotting import figure, show, output_file
from bokeh.sampledata.iris import flowers

colormap = {'setosa': 'red', 'versicolor': 'green', 'virginica': 'blue'}
colors = [colormap[x] for x in flowers['species']]

p = figure(title = "Iris Morphology")
p.xaxis.axis_label = 'Petal Length'
p.yaxis.axis_label = 'Petal Width'

p.circle(flowers["petal_length"], flowers["petal_width"],
         color=colors, fill_alpha=0.2, size=10)

output_file("iris.html", title="iris.py example")

show(p)

Which produces this plot

How can I add legend based on the color of the circle to the plot? Where:

• setosa : red
• versicolor : green
• virginica : blue

Answer 1

The easiest way that comes to mind is to define a ColumnDataSource to your plot to which you pass your data and from there reference the column with the "species" data from your dataframe.

Here is your code rework using this solution:

from bokeh.plotting import ColumnDataSource, figure, show, output_file
from bokeh.sampledata.iris import flowers

from bokeh.plotting import (ColumnDataSource, figure, show, output_file)
from bokeh.sampledata.iris import flowers

colormap = {'setosa': 'red', 'versicolor': 'green', 'virginica': 'blue'}
colors = [colormap[x] for x in flowers['species']]
flowers['colors'] = colors

source = ColumnDataSource(flowers)

p = figure(title = "Iris Morphology")
p.xaxis.axis_label = 'Petal Length'
p.yaxis.axis_label = 'Petal Width'

p.circle("petal_length", "petal_width",
         color='colors', fill_alpha=0.2, size=10, legend='species',source=source)
p.legend.location = "top_left"

output_file("iris.html", title="iris.py example")

show(p)

And this is what you should obtain. I additionally put the legend to the right so it is not inserted on top of the plot:

Answer 2

You can use for-loop to plot it:

from bokeh.plotting import figure, show, output_file
from bokeh.sampledata.iris import flowers

colormap = {'setosa': 'red', 'versicolor': 'green', 'virginica': 'blue'}
colors = [colormap[x] for x in flowers['species']]


p = figure(title = "Iris Morphology")
p.xaxis.axis_label = 'Petal Length'
p.yaxis.axis_label = 'Petal Width'


for specie in colormap.keys():
    df = flowers[flowers['species']==specie]
    p.circle(df["petal_length"], df["petal_width"],
             color=colormap[specie], fill_alpha=0.2, size=10, legend=specie)

p.legend.location = "top_left"


output_file("iris.html", title="iris.py example")

show(p)