Plot LINESTRING Z from GeoDataFrame using pydeck's PathLayer (or TripLayer) - geopandas

Question

I have a geodataframe with LINESTRING Z geometries:
TimeUTC
Latitude
Longitude
AGL
geometry
0
2021-06-16 00:34:04+00:00
42.8354
-70.9196
82.2
LINESTRING Z (42.83541343273769 -70.91961015378617 82.2, 42.83541343273769 -70.91961015378617 82.2)
1
2021-06-14 13:32:18+00:00
42.8467
-70.8192
66.3
LINESTRING Z (42.84674080836037 -70.81919357049679 66.3, 42.84674080836037 -70.81919357049679 66.3)
2
2021-06-18 23:56:05+00:00
43.0788
-70.7541
0.9
LINESTRING Z (43.07882882269921 -70.75414567194126 0.9, 43.07884601143309 -70.75416286067514 0, 43.07885174101104 -70.75416286067514 0, 43.07884028185512 -70.75415713109717 0, 43.07884601143309 -70.75414567194126 0, 43.07884601143309 -70.75414567194126 0)
I can plot the component points using pydeck's ScatterplotLayer using the raw
(not geo) dataframe but I need to also plot the full, smooth, track.
I've tried this:
layers = [
pdk.Layer(
type = "PathLayer",
data=tracks,
get_path="geometry",
width_scale=20,
width_min_pixels=5,
get_width=5,
get_color=[180, 0, 200, 140],
pickable=True,
),
]
view_state = pdk.ViewState(
latitude=gdf_polygon.centroid.x,
longitude=gdf_polygon.centroid.y,
zoom=6,
min_zoom=5,
max_zoom=15,
pitch=40.5,
bearing=-27.36)
r = pdk.Deck(layers=[layers], initial_view_state=view_state)
return(r)
Which silently fails. Try as I might, I cannot find a way to convert the
LINESTRING Z's (and I can do without the Z component if need be) to an object
that pydeck will accept.

Answer 1

I found a way to extract the info needed from GeoPandas and make it work in pydeck. You just need to apply a function that extracts the coordinates from the shapely geometries as a list. Here is a fully reproducible example:
import shapely
import numpy as np
import pandas as pd
import pydeck as pdk
import geopandas as gpd
linestring_a = shapely.geometry.LineString([[0,1,2],
[3,4,5],
[6,7,8]])
linestring_b = shapely.geometry.LineString([[7,15,1],
[8,14,2],
[9,13,3]])
multilinestring = shapely.geometry.MultiLineString([[[10,11,2],
[13,14,5],
[16,17,8]],
[[19,10,11],
[12,15,4],
[10,13,0]]])
gdf = gpd.GeoDataFrame({'id':[1,2,3],
'geometry':[linestring_a,
linestring_b,
multilinestring],
'color_hex':['#ed1c24',
'#faa61a',
'#ffe800']})
# Function that transforms a hex string into an RGB tuple.
def hex_to_rgb(h):
h = h.lstrip("#")
return tuple(int(h[i : i + 2], 16) for i in (0, 2, 4))
# Applying the HEX-to-RGB function above
gdf['color_rgb'] = gdf['color_hex'].apply(hex_to_rgb)
# Function that extracts the 2d list of coordinates from an input geometry
def my_geom_coord_extractor(input_geom):
if (input_geom is None) or (input_geom is np.nan):
return []
else:
if input_geom.type[:len('multi')].lower() == 'multi':
full_coord_list = []
for geom_part in input_geom.geoms:
geom_part_2d_coords = [[coord[0],coord[1]] for coord in list(geom_part.coords)]
full_coord_list.append(geom_part_2d_coords)
else:
full_coord_list = [[coord[0],coord[1]] for coord in list(input_geom.coords)]
return full_coord_list
# Applying the coordinate list extractor to the dataframe
gdf['coord_list'] = gdf['geometry'].apply(my_geom_coord_extractor)
gdf_polygon = gdf.unary_union.convex_hull
# Establishing the default view for the pydeck output
view_state = pdk.ViewState(latitude=gdf_polygon.centroid.coords[0][1],
longitude=gdf_polygon.centroid.coords[0][0],
zoom=4)
# Creating the pydeck layer
layer = pdk.Layer(
type="PathLayer",
data=gdf,
pickable=True,
get_color='color_rgb',
width_scale=20,
width_min_pixels=2,
get_path="coord_list",
get_width=5,
)
# Finalizing the pydeck output
r = pdk.Deck(layers=[layer], initial_view_state=view_state, tooltip={"text": "{id}"})
r.to_html("path_layer.html")
Here's the output it yields:
Big caveat
It seems like pydeck isn't able to deal with MultiLineString geometries. Notice how, in the example above, my original dataframe had 3 geometries, but only 2 lines were drawn in the screenshot.