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Bubble Charts in Python

How to make bubble charts in Python with Plotly.


New to Plotly?

Plotly is a free and open-source graphing library for Python. We recommend you read our Getting Started guide for the latest installation or upgrade instructions, then move on to our Plotly Fundamentals tutorials or dive straight in to some Basic Charts tutorials.

Bubble chart with plotly.express

A bubble chart is a scatter plot in which a third dimension of the data is shown through the size of markers. For other types of scatter plot, see the line and scatter page.

We first show a bubble chart example using Plotly Express. Plotly Express is the easy-to-use, high-level interface to Plotly, which operates on a variety of types of data and produces easy-to-style figures. The size of markers is set from the dataframe column given as the size parameter.

In [1]:
import plotly.express as px
df = px.data.gapminder()

fig = px.scatter(df.query("year==2007"), x="gdpPercap", y="lifeExp",
	         size="pop", color="continent",
                 hover_name="country", log_x=True, size_max=60)
fig.show()

Bubble Chart with plotly.graph_objects

If Plotly Express does not provide a good starting point, it is also possible to use the more generic go.Scatter class from plotly.graph_objects, and define the size of markers to create a bubble chart. All of the available options are described in the scatter section of the reference page: https://plotly.com/python/reference#scatter.

Simple Bubble Chart

In [2]:
import plotly.graph_objects as go

fig = go.Figure(data=[go.Scatter(
    x=[1, 2, 3, 4], y=[10, 11, 12, 13],
    mode='markers',
    marker_size=[40, 60, 80, 100])
])

fig.show()

Setting Marker Size and Color

In [3]:
import plotly.graph_objects as go

fig = go.Figure(data=[go.Scatter(
    x=[1, 2, 3, 4], y=[10, 11, 12, 13],
    mode='markers',
    marker=dict(
        color=['rgb(93, 164, 214)', 'rgb(255, 144, 14)',
               'rgb(44, 160, 101)', 'rgb(255, 65, 54)'],
        opacity=[1, 0.8, 0.6, 0.4],
        size=[40, 60, 80, 100],
    )
)])

fig.show()

Scaling the Size of Bubble Charts

To scale the bubble size, use the attribute sizeref. We recommend using the following formula to calculate a sizeref value:
sizeref = 2. * max(array of size values) / (desired maximum marker size ** 2)
Note that setting 'sizeref' to a value greater than 1, decreases the rendered marker sizes, while setting 'sizeref' to less than 1, increases the rendered marker sizes. See https://plotly.com/python/reference/scatter/#scatter-marker-sizeref for more information. Additionally, we recommend setting the sizemode attribute: https://plotly.com/python/reference/scatter/#scatter-marker-sizemode to area.

In [4]:
import plotly.graph_objects as go

size = [20, 40, 60, 80, 100, 80, 60, 40, 20, 40]
fig = go.Figure(data=[go.Scatter(
    x=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10],
    y=[11, 12, 10, 11, 12, 11, 12, 13, 12, 11],
    mode='markers',
    marker=dict(
        size=size,
        sizemode='area',
        sizeref=2.*max(size)/(40.**2),
        sizemin=4
    )
)])

fig.show()

Hover Text with Bubble Charts

In [5]:
import plotly.graph_objects as go

fig = go.Figure(data=[go.Scatter(
    x=[1, 2, 3, 4], y=[10, 11, 12, 13],
    text=['A<br>size: 40', 'B<br>size: 60', 'C<br>size: 80', 'D<br>size: 100'],
    mode='markers',
    marker=dict(
        color=['rgb(93, 164, 214)', 'rgb(255, 144, 14)',  'rgb(44, 160, 101)', 'rgb(255, 65, 54)'],
        size=[40, 60, 80, 100],
    )
)])

fig.show()

Bubble Charts with Colorscale

In [6]:
import plotly.graph_objects as go

fig = go.Figure(data=[go.Scatter(
    x=[1, 3.2, 5.4, 7.6, 9.8, 12.5],
    y=[1, 3.2, 5.4, 7.6, 9.8, 12.5],
    mode='markers',
    marker=dict(
        color=[120, 125, 130, 135, 140, 145],
        size=[15, 30, 55, 70, 90, 110],
        showscale=True
        )
)])

fig.show()

Categorical Bubble Charts

In [7]:
import plotly.graph_objects as go
import plotly.express as px
import pandas as pd
import math

# Load data, define hover text and bubble size
data = px.data.gapminder()
df_2007 = data[data['year']==2007]
df_2007 = df_2007.sort_values(['continent', 'country'])

hover_text = []
bubble_size = []

for index, row in df_2007.iterrows():
    hover_text.append(('Country: {country}<br>'+
                      'Life Expectancy: {lifeExp}<br>'+
                      'GDP per capita: {gdp}<br>'+
                      'Population: {pop}<br>'+
                      'Year: {year}').format(country=row['country'],
                                            lifeExp=row['lifeExp'],
                                            gdp=row['gdpPercap'],
                                            pop=row['pop'],
                                            year=row['year']))
    bubble_size.append(math.sqrt(row['pop']))

df_2007['text'] = hover_text
df_2007['size'] = bubble_size
sizeref = 2.*max(df_2007['size'])/(100**2)

# Dictionary with dataframes for each continent
continent_names = ['Africa', 'Americas', 'Asia', 'Europe', 'Oceania']
continent_data = {continent:df_2007.query("continent == '%s'" %continent)
                              for continent in continent_names}

# Create figure
fig = go.Figure()

for continent_name, continent in continent_data.items():
    fig.add_trace(go.Scatter(
        x=continent['gdpPercap'], y=continent['lifeExp'],
        name=continent_name, text=continent['text'],
        marker_size=continent['size'],
        ))

# Tune marker appearance and layout
fig.update_traces(mode='markers', marker=dict(sizemode='area',
                                              sizeref=sizeref, line_width=2))

fig.update_layout(
    title='Life Expectancy v. Per Capita GDP, 2007',
    xaxis=dict(
        title='GDP per capita (2000 dollars)',
        gridcolor='white',
        type='log',
        gridwidth=2,
    ),
    yaxis=dict(
        title='Life Expectancy (years)',
        gridcolor='white',
        gridwidth=2,
    ),
    paper_bgcolor='rgb(243, 243, 243)',
    plot_bgcolor='rgb(243, 243, 243)',
)
fig.show()

Reference

See https://plotly.com/python/reference/scatter/ for more information and chart attribute options!

What About Dash?

Dash is an open-source framework for building analytical applications, with no Javascript required, and it is tightly integrated with the Plotly graphing library.

Learn about how to install Dash at https://dash.plot.ly/installation.

Everywhere in this page that you see fig.show(), you can display the same figure in a Dash application by passing it to the figure argument of the Graph component from the built-in dash_core_components package like this:

import plotly.graph_objects as go # or plotly.express as px
fig = go.Figure() # or any Plotly Express function e.g. px.bar(...)
# fig.add_trace( ... )
# fig.update_layout( ... )

import dash
import dash_core_components as dcc
import dash_html_components as html

app = dash.Dash()
app.layout = html.Div([
    dcc.Graph(figure=fig)
])

app.run_server(debug=True, use_reloader=False)  # Turn off reloader if inside Jupyter