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Bubble Charts in Python

How to make bubble charts in Python with Plotly.

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 functions take as a first argument a tidy pandas.DataFrame. The size of markers is set from the dataframe column given as the size parameter.

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

fig = px.scatter(gapminder.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

When data are not available as tidy dataframes, it is also possible to use the more generic go.Scatter 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://plot.ly/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://plot.ly/python/reference/#scatter-marker-sizeref for more information. Additionally, we recommend setting the sizemode attribute: https://plot.ly/python/reference/#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://plot.ly/python/reference/#scatter for more information and chart attribute options!