point selection is not working

[diegozea]

Hi! I was trying the examples on Vega-Lite documentation, and I have found that this example works fine with interval but it doesn't work with point using VegaLite:

using ElectronDisplay
using VegaLite, VegaDatasets

data = dataset("cars")

julia> data |> @vlplot(:rect, x="Cylinders:o", y="Origin", 
           selection={pts={type="interval"}},
           color={condition={
               selection="pts",
               aggregate="count"
           }, value="grey"})

julia> data |> @vlplot(:rect, x="Cylinders:o", y="Origin", 
           selection={pts={type="point"}},
           color={condition={
               selection="pts",
               aggregate="count"
           }, value="grey"})

Gtk-Message: 19:17:09.779: GtkDialog mapped without a transient parent. This is discouraged.

Julia 1.6.2 & Ubuntu:

  [a93c6f00] DataFrames v1.2.2
  [d872a56f] ElectronDisplay v1.0.1
  [1a8c2f83] Query v1.0.0
  [efcf1570] Setfield v0.7.1
  [239c3e63] Vega v2.3.0
  [0ae4a718] VegaDatasets v2.1.1
  [112f6efa] VegaLite v2.6.0

P.S.: I am finding it hard to use VegaLite interactivity with @vlplot following the params documentation of Vega-Lite. It would be awesome to have a section on interactivity in the VegaLite.jl docs :)

[jeremiahpslewis]

Hey!

Just a few thoughts on debugging this:

1. It can be helpful to export the plot to a 'vegalite' json spec and check whether that is properly formatted by running it in-browser here

You can do this by appending |> save("test_plot.vegalite") to either of your plots

2. The plot works fine in-browser, so it's not your code and it's not the spec, it's a rendering issue on the package side.

3. You can get a more informative error message by trying to export your plot to a png, by appending |> save("test.png") to the plot that isn't working. This takes electron, etc. out of the picture.

4. If you do so, one gets the more informative, but still cryptic error message

Reprex:

data |> @vlplot(:rect, x="Cylinders:o", y="Origin",
                  selection={pts={type="point"}},
                  color={condition={
                      selection="pts",
                      aggregate="count"
                  }, value="grey"}) |> save("test.png")

TypeError: Cannot destructure property 'fields' of 'selectionConfig[selDef.type]' as it is undefined.
    at parseUnitSelection (/Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/node_modules/vega-lite/build/vega-lite.js:13924:9)
    at UnitModel.parseSelections (/Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/node_modules/vega-lite/build/vega-lite.js:25031:34)
    at UnitModel.parse (/Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/node_modules/vega-lite/build/vega-lite.js:20643:12)
    at Object.compile (/Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/node_modules/vega-lite/build/vega-lite.js:25305:13)
    at compile (/Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/vl2vg.js:18:27)
    at /Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/vl2vg.js:32:19
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at /Users/jeremiahlewis/.julia/artifacts/07b35f566ff32f265444804e50108d7f7f217576/node_modules/vega-cli/src/render.js:62:31
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
Errors encountered while save FileIO.File{FileIO.DataFormat{:PNG}, String}("test.png").

I think this likely indicates that we're hitting a Vega-lite js bug which is fixed in version 5.1.1 (browser version), but is present in 3.0.11, the version of Vega-lite which this package currently uses. See here. Unfortunately, binaries are still a pain point in this package which is otherwise astoundingly useful and fun for getting a nice plot on a page (and for < makie.jl scale datasets).

Sorry I can't provide a cure ATM, but hope the diagnosis is useful / accurate. ;)

[diegozea]

Thanks!

I can see the same error on my computer.

TypeError: Cannot destructure property 'fields' of 'selectionConfig[selDef.type]' as it is undefined.
    at parseUnitSelection (/home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/node_modules/vega-lite/build/vega-lite.js:13924:9)
    at UnitModel.parseSelections (/home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/node_modules/vega-lite/build/vega-lite.js:25031:34)
    at UnitModel.parse (/home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/node_modules/vega-lite/build/vega-lite.js:20643:12)
    at Object.compile (/home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/node_modules/vega-lite/build/vega-lite.js:25305:13)
    at compile (/home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/vl2vg.js:18:27)
    at /home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/vl2vg.js:32:19
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at /home/diego/.julia/artifacts/f22a465460a987b8219c0c4c44b4a94e443a9a4c/node_modules/vega-cli/src/render.js:62:31
    at processTicksAndRejections (internal/process/task_queues.js:97:5)