Ruimtelijke joins

Geospatiale data visualiseren in Python

Mary van Valkenburg

Data Science Program Manager, Nashville Software School

Raadsdistricten en schooldistricten

plot van 35 raadsdistricten

plot van 9 schooldistricten

Het .sjoin()-argument predicate

import geopandas as gpd

gpd.sjoin(blue_region_gdf, black_point_gdf, predicate = <how to build>)

predicate kan intersects, contains en within zijn

Gebruik van .sjoin()

plot van blauwe regio met zwarte punten

predicate = 'intersects'

gpd.sjoin(blue_region_gdf, black_point_gdf, predicate = 'intersects')

lichtblauwe polygoon met zwarte punten

predicate = 'contains'

gpd.sjoin(blue_region_gdf, black_point_gdf, predicate = 'contains')

lichtblauwe polygoon met zwarte punten

predicate = 'within'

gpd.sjoin(black_point_gdf, blue_region_gdf, predicate = 'within')

lichtblauwe polygoon met zwarte punten

Het .sjoin()-argument predicate - within

# vind raadsdistricten binnen schooldistricten

within_gdf = gpd.sjoin(council_districts, school_districts, predicate = 'within')

print('council districts within school districts: ', within_gdf.shape[0])

council districts within school districts:  11

Het .sjoin()-argument predicate - contains

# vind schooldistricten die raadsdistricten bevatten

contains_gdf = pd.sjoin(school_districts, council_districts, predicate = 'contains')

print('school districts contain council districts: ', contains_gdf.shape[0])

school districts contain council districts:  11

Het .sjoin()-argument predicate - intersects

# vind raadsdistricten die schooldistricten kruisen

intersect_gdf = gpd.sjoin(council_districts, school_districts, predicate = 'intersects')

print('council districts intersect school districts: ', intersect.shape[0])

council districts intersect school districts:  100

Kolommen in een ruimtelijk samengevoegde GeoDataFrame

within_gdf = gpd.sjoin(council_districts, school_districts, predicate = 'within')
within_gdf.head()

  first_name_left  last_name_left district_left  index_right    
0 Nick             Leonardo            1              0              
1 DeCosta          Hastings            2              0 
2 Nancy            VanReece            8              1    
3 Bill             Pridemore           9              1    
9 Doug             Pardue             10              1

# Agregeer raadsdistricten per schooldistrict - hernoem district_left en district_right
within_gdf.district_left = council_district
within_gdf.district_right = school_district
within_gdf[['council_district', 'school_district']
          ].groupby('school_district'
                   ).agg('count'
                        ).sort_values('council_district', ascending = False)

                   council_district 
school_district    
       3                   3
       1                   2
       9                   2
       2                   1
       5                   1
       6                   1
       8                   1

Laten we oefenen!

Geospatiale data visualiseren in Python