Fix DeckGL TextLayer issues

[MarcSkovMadsen]

Closes #5346

[MarcSkovMadsen]

The last issue I need to fix is how to handle the fact that DeckGL JS supports data rows containing lists like the coordinates value below. But the DeckGL pane does not.

The ColumnDataSource used to transfer the data does not support the coordinates list. Only -122.418466 ends up in the DeckGL data on the js side. 37.752254 is dropped along the way. See #5346 (comment)

data = {
        "layers": [
            {
                "@@type": "TextLayer",
                "data": [
                            {
                                "name": "24th St. Mission (24TH)",
                                "code": "24",
                                "address": "2800 Mission Street, San Francisco CA 94110",
                                "entries": 12817,
                                "exits": 12529,
                                "coordinates": [-122.418466, 37.752254]
                            }
                ],
            }
        ],
    }
    pane = DeckGL(data)

This can be handled in many ways

• 1: Enable using list/ array values.
  • That seems difficult as we assume data is columnar and we want to transfer it efficiently using ColumnDataSource.
• 2: Add validation to the DeckGL.object.
  • This could be done. But it could slow things down because there could be lots of rows to test if you want to test all the .data types supported. One place it could be done is when the ColumnDataSource is created. If we try to convert to a Pandas dataframe it raises an exception

cds.to_df()
*** ValueError: Per-column arrays must each be 1-dimensional

But again this could be a costly operation.

• 3: We could document this issue in the DeckGL reference notebook and provide an example where we on the python side convert the coordinates to two lat and long coordinates as in Serialization Error When Visualizing PyDeck TextLayer #5346 (comment)

Please advice @philippjfr. Thanks.

[codecov]

Codecov Report

Merging #5427 (edb106a) into main (78abc39) will decrease coverage by 2.43%.
The diff coverage is 25.00%.

❗ Current head edb106a differs from pull request most recent head 3d2dda7. Consider uploading reports for the commit 3d2dda7 to get more accurate results

@@            Coverage Diff             @@
##             main    #5427      +/-   ##
==========================================
- Coverage   72.59%   70.17%   -2.43%     
==========================================
  Files         274      274              
  Lines       39964    40005      +41     
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- Hits        29013    28073     -940     
- Misses      10951    11932     +981     

Flag	Coverage Δ
unitexamples-tests	70.17% <25.00%> (-2.43%)	⬇️

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Files Changed	Coverage Δ
panel/pane/deckgl.py	67.26% <21.73%> (-28.14%)	⬇️
panel/tests/pane/test_deckgl.py	72.79% <28.00%> (-27.21%)	⬇️

... and 14 files with indirect coverage changes

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[philippjfr]

This example does not yet work for me with this PR: https://deckgl.readthedocs.io/en/latest/gallery/text_layer.html

[philippjfr]

Nevermind, I see that this is because of the coordinates issue. Will fix.

[philippjfr]

Okay, fixed, i.e. implemented your suggestion 1.

This isn't actually difficult because the data is already serialized and sent correctly it just had to be correctly unpacked in JS.

[MarcSkovMadsen]

Thanks so much for finalizing this.