Help with the PathStyleExtension

[kentstephen]

Hi Kyle,

I searched for this extension on here and didn't see any discussions. I also did not find a specific example for this particular extension in the docs.

I have this snippet for a layer:

from lonboard import PathLayer
from lonboard.layer_extension import PathStyleExtension
extension=PathStyleExtension()
b_layer = PathLayer(
    # Select only a few attribute columns from the table
    table = road_table.select(["geometry"]),
    get_color=[255, 255, 255],
    get_width=20,
    get_dash_array=[10, 5],
    extensions=[extension],
    dash_justified=True
)

I'm trying to make this layer zebra'd. When I isolate this layer I see the roads in white, but no dashes.

I know get_dash_layer is required maybe I am missing something else.

[kylebarron]

Hmm. I didn't have an opportunity to actually test this code end to end before releasing (that's why there's no example). But I wanted to merge the contributed PR #487. I don't see anything obviously wrong with that invocation at a glance.

[kentstephen]

I dont think I am going to end up using the extension for this map afterall, but I would be happy take screenshots and provide anything else you would need to look into it.

[kylebarron]

You need to pass dash=True into the constructor of PathStyleExtension,

from lonboard.layer_extension import PathStyleExtension
extension = PathStyleExtension(dash=True)

layer = PathLayer.from_geopandas(
    gdf,
    width_min_pixels=0.8,
    get_dash_array=[10, 5],
    extensions=[extension],
    dash_justified=True
)
m = Map(layer)
m

This mirrors the upstream deck.gl API but is a bit unexpected. I'm not sure whether we should special case that. We should at least have better documentation for this