Plotly: How to show subplot titles at the bottom

Question

Given this example from plotly documentation

from plotly.subplots import make_subplots
import plotly.graph_objects as go

fig = make_subplots(
    rows=2, cols=2,
    specs=[[{}, {}],
           [{"colspan": 2}, None]],
    subplot_titles=("First Subplot","Second Subplot", "Third Subplot"))

fig.add_trace(go.Scatter(x=[1, 2], y=[1, 2]),
                 row=1, col=1)

fig.add_trace(go.Scatter(x=[1, 2], y=[1, 2]),
                 row=1, col=2)
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[2, 1, 2]),
                 row=2, col=1)

fig.update_layout(showlegend=False, title_text="Specs with Subplot Title")
fig.show()

Which is displayed as

How to change it so the subtitle is shown at the bottom?

Answer 1

As far as I know, there is no direct setting, so you can check the actual annotation position in fig.layout and adjust it.

from plotly.subplots import make_subplots
import plotly.graph_objects as go

fig = make_subplots(
    rows=2, cols=2,
    specs=[[{}, {}],
           [{"colspan": 2}, None]],
    subplot_titles=("First Subplot","Second Subplot", "Third Subplot"))

fig.add_trace(go.Scatter(x=[1, 2], y=[1, 2]),
                 row=1, col=1)

fig.add_trace(go.Scatter(x=[1, 2], y=[1, 2]),
                 row=1, col=2)
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[2, 1, 2]),
                 row=2, col=1)

fig.update_layout(showlegend=False, title_text="Specs with Subplot Title")
fig.layout.annotations[0].update(y=0.40)
fig.layout.annotations[1].update(y=0.40)
fig.layout.annotations[2].update(y=-0.2)

fig.show()

fig.layout
Layout({
    'annotations': [{'font': {'size': 16},
                     'showarrow': False,
                     'text': 'First Subplot',
                     'x': 0.225,
                     'xanchor': 'center',
                     'xref': 'paper',
                     'y': 1.0,
                     'yanchor': 'bottom',
                     'yref': 'paper'},
                    {'font': {'size': 16},
                     'showarrow': False,
                     'text': 'Second Subplot',
                     'x': 0.775,
                     'xanchor': 'center',
                     'xref': 'paper',
                     'y': 1.0,
                     'yanchor': 'bottom',
                     'yref': 'paper'},
                    {'font': {'size': 16},
                     'showarrow': False,
                     'text': 'Third Subplot',
                     'x': 0.5,
                     'xanchor': 'center',
                     'xref': 'paper',
                     'y': 0.375,
                     'yanchor': 'bottom',
                     'yref': 'paper'}],
    'showlegend': False,
    'template': '...',
    'title': {'text': 'Specs with Subplot Title'},
    'xaxis': {'anchor': 'y', 'domain': [0.0, 0.45]},
    'xaxis2': {'anchor': 'y2', 'domain': [0.55, 1.0]},
    'xaxis3': {'anchor': 'y3', 'domain': [0.0, 1.0]},
    'yaxis': {'anchor': 'x', 'domain': [0.625, 1.0]},
    'yaxis2': {'anchor': 'x2', 'domain': [0.625, 1.0]},
    'yaxis3': {'anchor': 'x3', 'domain': [0.0, 0.375]}
})