python - Adding labels in pie chart wedge in bokeh

Question

How do you add the information from a dataframe when creating a pie chart using bokeh?

I am using code from http://docs.bokeh.org/en/latest/docs/gallery/pie_chart.html

Basically, I want the values of each country in the wedge.

Answer 1

You're able to add text to a plot with a LableSet.

from math import pi
import pandas as pd
from bokeh.io import output_file, show
from bokeh.palettes import Category20c
from bokeh.plotting import figure
from bokeh.transform import cumsum
from bokeh.models import LabelSet, ColumnDataSource

output_file("pie.html")

x = {
    'United States': 157,
    'United Kingdom': 93,
    'Japan': 89,
    'China': 63,
    'Germany': 44,
    'India': 42,
    'Italy': 40,
    'Australia': 35,
    'Brazil': 32,
    'France': 31,
    'Taiwan': 31,
    'Spain': 29
}

data = pd.Series(x).reset_index(name='value').rename(columns={'index':'country'})
data['angle'] = data['value']/data['value'].sum() * 2*pi
data['color'] = Category20c[len(x)]

p = figure(plot_height=350, title="Pie Chart", toolbar_location=None,
           tools="hover", tooltips="@country: @value", x_range=(-0.5, 1.0))

p.wedge(x=0, y=1, radius=0.4,
        start_angle=cumsum('angle', include_zero=True), end_angle=cumsum('angle'),
        line_color="white", fill_color='color', legend='country', source=data)

data["value"] = data['value'].astype(str)
data["value"] = data["value"].str.pad(35, side = "left")
source = ColumnDataSource(data)

labels = LabelSet(x=0, y=1, text='value',
        angle=cumsum('angle', include_zero=True), source=source, render_mode='canvas')

p.add_layout(labels)

p.axis.axis_label=None
p.axis.visible=False
p.grid.grid_line_color = None

show(p)