Add a new `residuals_plot`?

[nvaytet]

This example shows how to make a plot of multiple lines with a residual difference panel below the main plot.

Is this something that is common enough that we could have a dedicated function for creating it?
For example, plopp.residual_plot(b, c, reference=a) would show 3 lines in the main panel and b-a and c-a in the residuals panel.

I guess it would be most useful if it could be used as a view in a graph of nodes, and not just a single purpose function.
This would mean that it could be used in combination with a slider, where both the main panel and the residuals would update when moving the slider.

[jl-wynen]

Kind of along the lines of your graph comment: Did you consider making these functions composable, e.g. using pp.plot(b, c).plot_residuals(reference=a, location=bottom). This could also be used to add slicers, etc.
Or would you rather people go through the graph directly?

[nvaytet]

Interesting, but I am now sure I get what would pp.plot(b, c).plot_residuals(reference=a, location=bottom) show?
And how would you add sliders with that syntax?

[jl-wynen]

It would create the base plot, then create the residuals plot from the data in the base plot and arrange everything into a single figure. Basically the same that your residual_plot would do except it goes through an intermediate plot (graph).

[nvaytet]

So in your example a would not show up on the main plot. Is that ok?

[jl-wynen]

What does plopp.residual_plot(b, c, reference=a) actually do? Does it plot 3 lines?

[nvaytet]

I thought you would have 3 lines in the main plot and 2 lines in the small panel below.

[nvaytet]

Actually, scratch that, I thought I had written plopp.residual_plot(a, b, c, reference=a) above...

[nvaytet]

So pp.plot(a, b, c).residuals(reference=a) ?

[jl-wynen]

Yes

[nvaytet]

I'm starting to think that to make this work in a generic way, we would need to be able to stitch two graphs together.

For example, the way I was first imagining I would implement this residuals_plot would be with 3 input nodes (for a, b, and c), one figure that takes all 3 as input. Then add 2 more nodes which do b-a and c-a, and then another figure that takes those two nodes as input.

But if you would like to use this as a final extra viz after you've performed other operations such as changing a fitting parameter with a slider, then you would want to add this 'sub-graph' to the other graph which has the slider, to make a large graph.

So maybe we do need a Graph object that would handle composing large graphs from smaller components, like the transform_coords? This would maybe make things like the slicing with a slider more re-usable?

[nvaytet]

Or maybe it's just that all the functions like plot or slicer should accept both Node and raw data as input.
They would then be very re-useable?

[nvaytet]

Or maybe it's just that all the functions like plot or slicer should accept both Node and raw data as input. They would then be very re-useable?

Continuing on this idea, I think we should use nodes a lot more in the high level plotting functions.
For example, all the data pre-processing we do at the start of the plot function is just operating on the raw input. Instead, the preprocessing step should just be another node in the graph.

[nvaytet]

See #254