Plot.ly: Different height for subplots with shared X-Axes

Question

Background

• Distinct subplots (✔) with same height (✘)

I can create a graph with Subplots with Shared X-Axes (example adapted from Plot.ly doc), with proper separation between subplots and where you can insert a specific title for each subplot via subplot_titles:

from plotly import tools
import plotly.plotly as py
import plotly.graph_objs as go

trace1 = go.Scatter(
    x=[0, 1, 2],
    y=[10, 11, 12]
)
trace2 = go.Scatter(
    x=[2, 3, 4],
    y=[100, 110, 120],
)
trace3 = go.Scatter(
    x=[3, 4, 5],
    y=[1000, 1100, 1200],
)
fig = tools.make_subplots(rows=3, cols=1, specs=[[{}], [{}], [{}]],
                          shared_xaxes=True, shared_yaxes=True,
                          vertical_spacing=0.1, subplot_titles=('subtitle 1', 
                          'subtitle 2', 'subtitle 3'))
fig.append_trace(trace1, 3, 1)
fig.append_trace(trace2, 2, 1)
fig.append_trace(trace3, 1, 1)

fig['layout'].update(height=600, width=600, title='Subplots with Shared X-Axes')
py.plot(fig, filename='subplots-shared-xaxes')

• Merged subplots (✘) with distinct height (✔)

I can also create a graph with Stacked Subplots with a Shared X-Axis (example adapted from Plot.ly doc), where you can define the relative height of each subplot via domain:

from plotly import tools
import plotly.plotly as py
import plotly.graph_objs as go

trace1 = go.Scatter(
    x=[0, 1, 2],
    y=[10, 11, 12]
)
trace2 = go.Scatter(
    x=[2, 3, 4],
    y=[100, 110, 120],
    yaxis='y2'
)
trace3 = go.Scatter(
    x=[3, 4, 5],
    y=[1000, 1100, 1200],
    yaxis='y3'
)
data = [trace1, trace2, trace3]
layout = go.Layout(
    yaxis=dict(
        domain=[0, 0.25]
    ),
    legend=dict(
        traceorder='reversed'
    ),
    yaxis2=dict(
        domain=[0.25, 0.75]
    ),
    yaxis3=dict(
        domain=[0.75, 1]
    )
)
fig = go.Figure(data=data, layout=layout)
fig['layout'].update(height=600, width=600, title='Stacked Subplots with Shared X-Axes')
py.plot(fig, filename='stacked-subplots-shared-x-axis')

Question

How to to create subplots with shared x-axes where you have both a title (fig 1) and different relative height (fig 2) for each subplot?

---

What I have tried

• Using subplots and rowspan

A first hack is to create an additional row make a plot span over two of them:

from plotly import tools
import plotly.plotly as py
import plotly.graph_objs as go

trace1 = go.Scatter(
    x=[0, 1, 2],
    y=[10, 11, 12]
)
trace2 = go.Scatter(
    x=[2, 3, 4],
    y=[100, 110, 120],
)
trace3 = go.Scatter(
    x=[3, 4, 5],
    y=[1000, 1100, 1200],
)
fig = tools.make_subplots(
    rows=4,
    cols=1,
    specs=[
        [{}],
        [{'rowspan':2}],
        [None],
        [{}],
    ],
    shared_xaxes=True,
    shared_yaxes=True,
    vertical_spacing=0.1,
    subplot_titles=(
        'subtitle 1',
        'subtitle 2',
        None,
        'subtitle 3',
    )
)
fig.append_trace(trace3, 1, 1)
fig.append_trace(trace2, 2, 1)
fig.append_trace(trace1, 4, 1)

fig['layout'].update(height=600, width=600, title='Subplots with Shared X-Axes, span rows')
py.plot(fig, filename='subplots-shared-x-axis-span-rows', auto_open=True)

The result is exactly what I want to achieve. However, this hack seems wrong to me: syntactically speaking, I don't want a graph that spans over two rows. Moreover, having to add [None] to specs and None to subplot_titles is ugly and error-prone if you want to modify anything.

Consider also the case where you want a 13% | 70% | 17% height distribution of subplots!

• using domain

A slightly better option is to use update axes with domain, yet subplot titles get messed up (they are still evenly vertically distributed):

from plotly import tools
import plotly.plotly as py
import plotly.graph_objs as go

trace1 = go.Scatter(
    x=[0, 1, 2],
    y=[10, 11, 12]
)
trace2 = go.Scatter(
    x=[2, 3, 4],
    y=[100, 110, 120],
)
trace3 = go.Scatter(
    x=[3, 4, 5],
    y=[1000, 1100, 1200],
)
fig = tools.make_subplots(
    rows=3,
    cols=1,
    specs=[[{}], [{}], [{}]],
    shared_xaxes=True,
    shared_yaxes=True,
    vertical_spacing=0.1,
    subplot_titles=(
        'subtitle 1',
        'subtitle 2',
        'subtitle 3'
    )
)
fig.append_trace(trace1, 3, 1)
fig.append_trace(trace2, 2, 1)
fig.append_trace(trace3, 1, 1)

fig['layout'].update(height=600, width=600, title='Subplots with Shared X-Axes and `domain` hack')
fig['layout']['yaxis1'].update(domain=[0, 0.2])
fig['layout']['yaxis2'].update(domain=[0.3, 0.7])
fig['layout']['yaxis3'].update(domain=[0.8, 1])
py.plot(fig, filename='subplots-shared-x-axis-domain-hack', auto_open=True)

Answer 1

This bug has been solved by Kully in PR #1245 and fixed in dash v3.4.0.

Following code — using only 3 subplots and row_width=[0.2, 0.4, 0.2] — should thus work flawlessly:

from plotly import tools
import plotly.plotly as py
import plotly.graph_objs as go

trace1 = go.Scatter(
    x=[0, 1, 2],
    y=[10, 11, 12]
)
trace2 = go.Scatter(
    x=[2, 3, 4],
    y=[100, 110, 120],
)
trace3 = go.Scatter(
    x=[3, 4, 5],
    y=[1000, 1100, 1200],
)
fig = tools.make_subplots(rows=3, cols=1,
                          shared_xaxes=True,
                          vertical_spacing=0.1,
                          subplot_titles=('subtitle 1', 'subtitle 2', 'subtitle 3'),
                          row_width=[0.2, 0.4, 0.2]
                         )

fig.append_trace(trace1, 3, 1)
fig.append_trace(trace2, 2, 1)
fig.append_trace(trace3, 1, 1)

fig['layout'].update(height=600, width=600, title='Subplots with Shared X-Axes')
go.FigureWidget(fig)