H3 neighbourhood

In [1]:

from srai.neighbourhoods import H3Neighbourhood
from srai.regionalizers import H3Regionalizer, geocode_to_region_gdf
from srai.plotting.folium_wrapper import plot_neighbours, plot_all_neighbourhood

from srai.neighbourhoods import H3Neighbourhood from srai.regionalizers import H3Regionalizer, geocode_to_region_gdf from srai.plotting.folium_wrapper import plot_neighbours, plot_all_neighbourhood

In [2]:

gdf_sf = geocode_to_region_gdf("Wrocław, PL")
regions_gdf = H3Regionalizer(8).transform(gdf_sf)

gdf_sf = geocode_to_region_gdf("Wrocław, PL") regions_gdf = H3Regionalizer(8).transform(gdf_sf)

Region somewhere in the middle of the area under analysis¶

Direct neighbours¶

In [3]:

neighbourhood_with_regions = H3Neighbourhood(regions_gdf)
region_id = "881e204089fffff"
neighbours_ids = neighbourhood_with_regions.get_neighbours(region_id)
plot_neighbours(regions_gdf, region_id, neighbours_ids)

neighbourhood_with_regions = H3Neighbourhood(regions_gdf) region_id = "881e204089fffff" neighbours_ids = neighbourhood_with_regions.get_neighbours(region_id) plot_neighbours(regions_gdf, region_id, neighbours_ids)

Out[3]:

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Only 3rd ring¶

In [4]:

neighbours_ids = neighbourhood_with_regions.get_neighbours_at_distance(region_id, 3)
plot_neighbours(regions_gdf, region_id, neighbours_ids)

neighbours_ids = neighbourhood_with_regions.get_neighbours_at_distance(region_id, 3) plot_neighbours(regions_gdf, region_id, neighbours_ids)

Out[4]:

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Regions up to distance 3¶

In [5]:

neighbours_ids = neighbourhood_with_regions.get_neighbours_up_to_distance(region_id, 3)
plot_neighbours(regions_gdf, region_id, neighbours_ids)

neighbours_ids = neighbourhood_with_regions.get_neighbours_up_to_distance(region_id, 3) plot_neighbours(regions_gdf, region_id, neighbours_ids)

Out[5]:

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Full neighbourhood¶

In [6]:

plot_all_neighbourhood(regions_gdf, region_id, neighbourhood_with_regions)

plot_all_neighbourhood(regions_gdf, region_id, neighbourhood_with_regions)

Out[6]:

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Edge region¶

The Neighbourhood only returns the indices of available regions if provided with regions_gdf

In [7]:

edge_region_id = "881e2050bdfffff"
neighbours_ids = neighbourhood_with_regions.get_neighbours(edge_region_id)
print(neighbours_ids)

edge_region_id = "881e2050bdfffff" neighbours_ids = neighbourhood_with_regions.get_neighbours(edge_region_id) print(neighbours_ids)

{'881e2050abfffff', '881e2050b5fffff', '881e205087fffff', '881e2050a3fffff'}

In [8]:

plot_neighbours(regions_gdf, edge_region_id, neighbours_ids)

plot_neighbours(regions_gdf, edge_region_id, neighbours_ids)

Out[8]:

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On the other hand, an "unbiased" H3Neighbourhood returns all 6 neighbours from H3.

In [9]:

neighbourhood_without_regions = H3Neighbourhood()
neighbourhood_without_regions.get_neighbours(edge_region_id)

neighbourhood_without_regions = H3Neighbourhood() neighbourhood_without_regions.get_neighbours(edge_region_id)

Out[9]:

{'881e205087fffff',
 '881e2050a3fffff',
 '881e2050abfffff',
 '881e2050b1fffff',
 '881e2050b5fffff',
 '881e2050b9fffff'}

Regions with a gap¶

One thing to note when using the H3Neighbourhood is that it uses the h3 library under the hood. The only post-processing step is to select from among the regions under analysis. Due to that some neighbours can be included as K-th neighbours, even if there is no path of length K between them and the regions you ask for. This is because H3 still treats them as a part of the K-th ring. An example is shown below

In [10]:

edge_region_id = "881e2050bdfffff"
neighbours_ids = neighbourhood_with_regions.get_neighbours_at_distance(edge_region_id, 2)
print(neighbours_ids)

edge_region_id = "881e2050bdfffff" neighbours_ids = neighbourhood_with_regions.get_neighbours_at_distance(edge_region_id, 2) print(neighbours_ids)

{'881e2050b7fffff', '881e2050a7fffff', '881e204249fffff', '881e2050a1fffff', '881e2050b3fffff', '881e20424bfffff'}

In [11]:

plot_neighbours(regions_gdf, edge_region_id, neighbours_ids)

plot_neighbours(regions_gdf, edge_region_id, neighbours_ids)

Out[11]:

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In [12]:

plot_all_neighbourhood(regions_gdf, edge_region_id, neighbourhood_with_regions)

plot_all_neighbourhood(regions_gdf, edge_region_id, neighbourhood_with_regions)

Out[12]:

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