Proper syntax for a pydeck PathLayer from a shapely geometry

I see the example of a PathLayer and it shows the input data is a list of lists within a regular pandas df, as opposed to a geopandas df.

Let's say I'm coming from a GeoPandas df (let's say called consline) that has a shapely MULTILINESTRING geometry column. What's the proper/best syntax to use that? I tried different combinations between calling it a PathLayer and a GeoJsonLayer with using the get_path parameter and nothing seemed to work except for doing json.loads(consline.geometry.to_json())['features'][0]['geometry']['coordinates']

The consline can be loaded as

consline=gpd.read_file("https://github.com/deanm0000/SOexamples/raw/main/consline.gpkg")

For instance, this doesn't work:

mylayers=[
    pdk.Layer(
        'PathLayer',
        data=consline,
        get_path="geometry",
        pickable=True,
        get_fill_color=[0,255,0],
        width_scale=20,
        width_min_pixels=2,   
    )
]
view_state = pdk.ViewState(
    longitude=-98.99,
    latitude=31.79,
    zoom=5,
    min_zoom=1,
    max_zoom=15)
r = pdk.Deck(layers=mylayers, initial_view_state=view_state, map_style='light')
r.to_html("example.html")

but this does:

mylayers=[
    pdk.Layer(
    'PathLayer',
    data=json.loads(consline.geometry.to_json())['features'][0]['geometry']['coordinates'],
    get_path="-",
    pickable=True,
    get_fill_color=[0,255,0],
    width_scale=20,
    width_min_pixels=2,
)
]
view_state = pdk.ViewState(
    longitude=-98.99,
    latitude=31.79,
    zoom=5,
    min_zoom=1,
    max_zoom=15)
r = pdk.Deck(layers=mylayers, initial_view_state=view_state, map_style='light')
r.to_html("example.html")

I can't imagine having shapely convert it to json and then python to convert it to a dict and then have pydeck convert it back to json for deck.gl is the best way to do this but I can't get it to work any other way.

Solution

You can set data to an object having the shape described for the deck.gl PathLayer.

Using shapely, you can merge the MULTILINESTRING to a LINESTRING. Then pass along its coordinates.

With default get_path option set to d => d.path

import shapely as shp

consline_geoseries = consline.geometry.iloc[0]
consline_linestring = shp.ops.linemerge(consline_geoseries)
data = [{'path': list(consline_linestring.coords)}]

mylayers=[
    pdk.Layer(
        'PathLayer',
        data=data,
        pickable=True,
        get_fill_color=[0,255,0],
        width_scale=20,
        width_min_pixels=2,   
    )
]

With default get_path set to -

import shapely as shp

consline_multilinestring = consline.geometry.iloc[0]
consline_linestring = shp.ops.linemerge(consline_multilinestring)
data = [list(consline_linestring.coords)]

mylayers=[
    pdk.Layer(
        'PathLayer',
        data=data,
        get_path='-',
        pickable=True,
        get_fill_color=[0,255,0],
        width_scale=20,
        width_min_pixels=2,   
    )
]

If you don't want to use shapely, you can pass the MULTILINESTRING as a data list of LINESTRING.

consline_multilinestring = consline.geometry[0]
mylayers=[
    pdk.Layer(
        'PathLayer',
        data=[list(geom.coords) for geom in consline_multilinestring.geoms],
        get_path="-",
        pickable=True,
        get_fill_color=[0,255,0],
        width_scale=20,
        width_min_pixels=2,   
    )
]