Python Bokeh - Making a Pie Chart

Last Updated : 28 Jul, 2020

Bokeh is a Python interactive data visualization. It renders its plots using HTML and JavaScript. It targets modern web browsers for presentation providing elegant, concise construction of novel graphics with high-performance interactivity. Let us see how to plot a pie chart in Bokeh. Does not provide us a module to directly plot a pie chart but we can use the wedge glyphs to make the pie chart. Wedges can be plotted using the bokeh.plotting.figure.wedge() function. In the wedge() function, the primary parameters are the x and y coordinates of the wedge, the radius, the start_angle and the end_angle of the wedge. In order to plot the wedges in such a way that they look like a pie chart, the x, y, and radius parameters of all the wedges will be the same. We will only adjust the start_angle and the end_angle. Example 1 :

Python3 1==

# importing the modules
from bokeh.plotting import figure, output_file, show

# file to save the model 
output_file("gfg.html") 
         
# instantiating the figure object 
graph = figure(title = "Bokeh Pie Chart") 

# center of the pie chart
x = 0
y = 0

# radius of the glyphs
radius = 1

# starting angle values
start_angle = [0, 1.8, 2.5,
               3.7, 5.6]

# ending angle values
end_angle = [1.8, 2.5, 3.7,
             5.6, 0]

# color of the wedges
color = ["violet", "blue", "green",
          "yellow", "red"]

# plotting the graph
graph.wedge(x, y, radius,
            start_angle,
            end_angle,
            color = color)

# displaying the graph
show(graph)

Output :

Example 2 : In his example we will be visualizing some data. In the data we are provided with the Share of sectors in GVA during 2017-18 in India. The shares are :

Agriculture - 17.1%
Industry - 29.1%
Services - 53.8%

To find the start_angle and the end_angle we will need to convert the percentages into radians using the following formula :

math.radians((percent / 100) * 360)

Python3 1==

# importing the modules
from bokeh.plotting import figure, output_file, show
import math

# file to save the model 
output_file("gfg.html") 
         
# instantiating the figure object 
graph = figure(title = "Bokeh Pie Chart") 

# name of the sectors
sectors = ["Agriculture", "Industry", "Services"]

# % tage weightage of the sectors
percentages = [17.1, 29.1, 53.8]

# converting into radians
radians = [math.radians((percent / 100) * 360) for percent in percentages]

# starting angle values
start_angle = [math.radians(0)]
prev = start_angle[0]
for i in radians[:-1]:
    start_angle.append(i + prev)
    prev = i + prev

# ending angle values
end_angle = start_angle[1:] + [math.radians(0)]

# center of the pie chart
x = 0
y = 0

# radius of the glyphs
radius = 1

# color of the wedges
color = ["yellow", "red", "lightblue"]

# plotting the graph
for i in range(len(sectors)):
    graph.wedge(x, y, radius,
                start_angle = start_angle[i],
                end_angle = end_angle[i],
                color = color[i],
                legend_label = sectors[i])

# displaying the graph
show(graph)