Subplots

Introduction to Data Visualization with Plotly in Python

Alex Scriven

Data Scientist

What are subplots?

Subplots: 'mini-plots' positioned in a grid

Show different plot types (same data) or different data subsets

Subplots outline

A reminder of traces

Plotly figures contain a list of traces - the data and type
Accessed using fig.data[0], fig.data[1]
- Can add to subplots using .add_trace()

px_fig = px.scatter(df...)
print(px_fig)

Figure({'data': [trace1], 'layout': {...}})

Creating a 1x2 subplot

import plotly.express as px
from plotly.subplots import make_subplots

# Create a subplot grid
fig = make_subplots(rows=2, cols=1)

# Create plotly express figures
hist = px.histogram(revenues, x='Revenue')
box = px.box(revenues, x='Revenue')

# Extract traces and add to subplots
fig.add_trace(hist.data[0], row=1, col=1)
fig.add_trace(box.data[0], row=2, col=1)

fig.show()

A finance subplot

Customizing subplots

No overall plot title
No subplot titles

✨ Make it presentation-worthy

simple finance subplot

Subplot titles

from plotly.subplots import make_subplots

fig = make_subplots(rows=2, cols=1,
    subplot_titles=[
    'Histogram of company revenues', 
    'Box plot of company revenues'])

## Add in traces (fig.add_trace())

fig.update_layout({'title': {'text':
    'Plots of company revenues', 
    'x': 0.5, 'y': 0.9}})

fig.show()

Subplot titles fixed

Stacked subplots

fig = make_subplots(rows=3, cols=1, 
  subplot_titles=['Adelie Penguins'
  , 'Gentoo Penguins', 'Chinstrap Penguins'])

row_num = 1
for species in ['Adelie', 'Gentoo', 'Chinstrap']:
  # Filter data for this species
  df = penguins[penguins['Species'] == species]

  scatter = px.scatter(df, x='Culmen Length (mm)'
  , y='Culmen Depth (mm)')
  # Add the trace to the subplot
  fig.add_trace(scatter.data[0]
  , row=row_num, col=1)
  row_num +=1

Penguins subplots stacked

Subplots with shared axes

Making the x-axis 'shared':

fig = make_subplots(
    rows=3, cols=1
    , shared_xaxes=True)

shared x-axis penguin subplots

Let's practice!

Introduction to Data Visualization with Plotly in Python