GeoPandas Support (GeoPandas and Shapely)

GeoPandas GeoDataFrame is a tabular data structure that contains a set of shapes (geometry) per each observation.

GeoDataFrame extends pandas DataFrame and as such, aside from the geometry, can contain other data.

GeoPandas supports the following three basic classes of geometric objects (shapes):

  • Points / Multi-Points

  • Lines / Multi-Lines

  • Polygons / Multi-Polygons

All GeoPandas shapes are “understood” by Lets-Plot and can be plotted using various geometry layers, depending on the type of the shape.

Use:

Plot Preliminaries

import pandas as pd

from lets_plot.geo_data import *
from lets_plot import *
LetsPlot.setup_html()

df = pd.DataFrame({
    'state': ['IL', 'IN', 'MI', 'OH', 'WI'],
    'pop_2021': [12_569_321, 6_805_663, 9_992_427, 11_714_618, 5_852_490],
})
gdf = geocode_states(names=df.state).scope('US').get_boundaries()[['state', 'geometry']]
The geodata is provided by © OpenStreetMap contributors and is made available here under the Open Database License (ODbL).

Use Cases

Depending on the situation, for spatial data we use either parameter data or map or both.

Use either data or map Parameter

Suppose we have the following data:

gdf
state geometry
0 IL MULTIPOLYGON (((-89.20898 37.02010, -89.12109 ...
1 IN MULTIPOLYGON (((-87.62695 37.92687, -87.62695 ...
2 MI MULTIPOLYGON (((-88.41797 46.01222, -88.50586 ...
3 OH MULTIPOLYGON (((-82.17773 38.75408, -82.17773 ...
4 WI MULTIPOLYGON (((-92.81250 45.02695, -92.81250 ...
If you want to draw only shapes, then it makes no difference which parameter is used:
ggplot() + geom_map(data=gdf)
ggplot() + geom_map(map=gdf)

Use data Parameter

If you want to use aesthetics, the data parameter is the only choice:

ggplot() + geom_map(aes(fill='state'), color='white', data=gdf)

Use Both: data and map Parameters

Suppose you also have a dataframe with population data:

df
state pop_2021
0 IL 12569321
1 IN 6805663
2 MI 9992427
3 OH 11714618
4 WI 5852490
In this situation, in order to link aesthetics to the population numbers you will use:
  • data parameter for the “population” dataframe,

  • map parameter for the state boundaries GeoDataframe.

The 3rd parameter, map_join, will help to combine population values and state boundaries on the same chart:

ggplot() + geom_map(aes(fill='pop_2021'), color='white', data=df, map=gdf, map_join='state')

use_crs Parameter

Specify EPSG code of coordinate reference system (CRS). All coordinates in GeoDataFrame will be projected to this CRS.

ggplot() + geom_map(map=gdf, use_crs="EPSG:32616")
Value “provided” tells Lets-Plot that the input GeoDataframe already contains coordinates in the desired CRS and should not be reprojected any further.
gdf_utm = gdf.to_crs("EPSG:32616")
ggplot() + geom_map(map=gdf_utm, use_crs="provided")

Examples

  • The world map with Lets-Plot and GeoPandas: Using Lets-Plot with GeoPandas to Create Maps

  • Plotting Airbnb prices Boston: Plotting Airbnb prices Boston

  • Spatial prediction of soil pollutants with multi-output Gaussian processes: Spatial prediction of soil pollutants with multi-output Gaussian processes

  • Using geom_imshow() to draw DEM on map: DEM image on map

  • use_crs parameter: Image on map, the 'use_crs' parameter

  • Using exotic map projections: Using exotic map projections

  • An inset map of Kotlin island: Inset map of Kotlin island

Couldn't load kotlin_island.png