Can I use link_selections with combined plots in Holoviews?

Question

I would like to link selections across several elements, one of which is actually a 'Overlay' (typically plot1*plot2). However, I have not been able to make it work.

Indeed, after being initialized link_selections is set by passing as an argument a layout that contains elements sharing the same Dataset. For instance, looking at the example provided by Holoviews in the user guide:

w_accel_scatter = hv.Scatter(autompg_ds, 'weight', 'accel')
mpg_hist = histogram(autompg_ds, dimension='mpg', normed=False).opts(color="green")
violin = hv.Violin(autompg_ds, [], 'hp')

mpg_ls = link_selections.instance()    
mpg_ls(w_accel_scatter + mpg_hist + violin)

In my case I would like to display, say, w_accel_scatter*line_plot + mpg_hist + violin (with line_plot using other data), while retaining the selection link between w_accel_scatter, mpg_hist and violin:

The problem is that calling mpg_ls() actually triggers the display of what is passed as an argument and obviously mpg_ls(w_accel_scatter*other_plot + mpg_hist + violin) won't work.

Btw I am working within a notebook and using the bokeh backend. Any help would be appreciated!

Answer 1

I'm not sure what you mean by "calling mpg_ls() actually triggers the display of what is passed as an argument". Returning an object as the value of a cell is what triggers the display, not mpg_ls, so you should be able to keep working after your mpg_ls call. You just need to capture the result of your mpg_ls call, and then you can work with it until you eventually have something you want to display.

In any case, because nothing should be displayed immediately when you do mpg_ls(), you can pass each object you want linked to mpg_ls independently, linking each of the ones you want to link, then put them all into whatever overlay or layout you want.

ETA an example of doing precisely that:

mpg_ls = link_selections.instance()
other_plot = hv.Curve(([2000,4000,5000], [10,15,25])).opts(color="red")
mpg_ls(w_accel_scatter)*other_plot + mpg_ls(mpg_hist) + mpg_ls(violin)

Here we specifically link only those plots that are related to each other, and not the unrelated other_plot. We should clarify how to do this in the docs, because it's not obvious! Also, I would have expected mpg_ls(w_accel_scatter*other_plot + mpg_hist + violin) to work, which I'll file as an issue on HoloViews.