Plotly Express template margin issue

[fullpwemium]

Hello,

If I use px for a scatter plot with margin right and bottom set to 0, I get some strange margin on the right anyway

fig = px.scatter(data, x='x', y='y')
fig.update(layout = go.Layout(margin=dict(t=0,r=0,b=40,l=40)))

The same works fine using

fig = go.Figure()

If I try to set a default layout

import plotly.io as pio          # to set mine plot layout
pio.templates['mine'] = pio.to_templated(go.Figure().update_layout(plot_bgcolor='rgba(200,200,200,1)',legend=dict(orientation="h",y=1.1, x=.5, xanchor='center'),margin=dict(t=0,r=0,b=40,l=40))).layout.template
pio.templates.default = 'mine'

It works fine for

fig = go.Figure()

but for

fig = px.scatter(data, x='x', y='y')
fig.show()

I get large padding on top, and the same weird little bit on the right.

I refer to the margin on the right as weird because when I do

fig.layout

I only se

'margin': {'t': 60},

Even if I do

fig.update(layout = go.Layout(margin=dict(t=0,r=0,b=40,l=40)))

afterwards, I still have the weird right margin. No the same issue with go.Figure()

[fullpwemium]

Strangest thing, passing in title=" " (or just any title) applies my margins for px.line

[nicolaskruchten]

So PX does do things a bit differently when the title is present: https://github.com/plotly/plotly.py/blob/master/packages/python/plotly/plotly/express/_core.py#L1026

But I’m not sure why this would result in the behaviour described above. I’ll dig into it :)

[fullpwemium]

Hi @nicolaskruchten thanks for looking at the issue

I think I found it too albeit in a different version of _core I was look at by mistake...

https://github.com/plotly/plotly_express/blob/f6b513fbad2b7171c729f9ef0b4c77d27afebb21/plotly_express/_core.py

Line 865

if "title" not in layout_patch:
        layout_patch["margin"] = {"t": 60}

why would the top margin be overriden if the title is missing?

this doesn't explain the weird padding on the right

[nicolaskruchten]

PX does this just to balance the whitespace above and below the plot... perhaps it's too opinionated. I'm still not sure why it impacts the right margin.

[fullpwemium]

@nicolaskruchten any ideas on how to fix the issues if we have a template with margins set to 0

[nicolaskruchten]

So I can't replicate the differences you're seeing with and without title, but I can explain why px-created figures have what appears like a bit more right-margin. It's because of the xaxis.domain which is set to [0, 0.98] for a single-subplot px figure, rather than the default [0,1].

[fullpwemium]

@nicolaskruchten thanks for the hint - it is indeed xaxis.domain. Unfortunately setting this to [0,1] in my template is ignored by plotly.express, I have to use fig.update_layout(xaxis=dict(domain=[0,1])) after every figure...

I will try put a MWE for the title issue soon

[nicolaskruchten]

Yes, the domains are set explicitly from within PX, so it will never respect the template settings.

That said, @jonmmease what's the reasoning for having the single-subplot case have a domain that's not [0,1] ? Is this something I had in the pre-make_subplots version that got carried over or is it something that make_subplots does or...?

[gvwilson]

Hi - we are currently trying to tidy up Plotly's public repositories to help us focus our efforts on things that will help users most. Since this issue has been sitting for several years, I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our backlog. Thanks for your help - @gvwilson