Interactive plot data inspection with Makie (à la PlotlyJS)

What’s the latest on being able to inspect data interactively in Makie? I mean something similar to what PlotlyJS has by default, where you can for example point the cursor at a point in a scatter plot and it will give you a tooltip showing the coordinates of that point:


(from 3D Scatter Plots | JavaScript | Plotly)


My understanding is that the missing puzzle piece is 3D (and 2D for API consistency) object picking. Because then you could tie observables to show/hide the billboard with the related data of your choice. I don’t know how much of an implementation effort this is.

+1 on missing this feture a lot

It’s not that this particularly hard to do, it’s just that nobody took the time to do it yet. As quick proof of concept:

using GLMakie
fig, ax, p = scatter(rand(Point3f0, 100))
t = text!(ax, " ", position = first(p[1][]), visible = false, halign = :left)

on(events(fig.scene).mouseposition) do mp
    plt, idx = mouse_selection(fig.scene)
    if plt == p && idx != nothing
        t.position = p[1][][idx]
        t[1] = string(p[1][][idx])
        t.visible = true
        t.visible = false

It gets harder for things that don’t have a one to one correspondence of picking index to plot data. Try it with a barplot, for example. The other harder thing might be to get it to work without having to point exactly at specific pixels. It is very annoying to use if you have to perfectly have to point at 0.5 px wide lines

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It is very annoying to use if you have to perfectly have to point at 0.5 px wide lines

We have a pick(scene, mouseposition, range) which should help with that.

And sure, some plots will require some extra work to behave nicely, but it’s not like we’re missing something fundamental like point picking.


So the range thing is for that purpose? I’ve never seen it in use. And yes, the fundamental thing is there (though it would be nice to have picking in WGLMakie so all the widgets etc work there as well) but in my experience the gap to having something that feels nice to use can still be pretty wide. Just to manage expectations :slight_smile:

Microsoft’s SandDance has a nice version of this. It’s open source and it’s available as a vscode extension. It might have some good inspiration.


@jzr, wow! Thanks for this exceptional tip. SandDance is probably the best thing since sliced bread.

The plot below was done with two mouse clicks: (i) drag CSV file to VSCode data tree, and (ii) right click file to View it in SandDance; and voilà:


Adapting this a little bit, I’m trying to use hlines! and vlines! to draw lines from the point being inspected to the y and x axes. The xmax and ymax arguments are in axis space though, whereas I’d like to specify this in data space. Is that possible? Or should I just be simply drawing ordinary lines from the x- and y-axis? Either way is there a function for transforming between data and axis space? I tried searching the docs but couldn’t come up with it.