TechnicalGIS

#LSOA

2 posts

Tutorial Python Part 2 of 3

Spatial joins in GeoPandas: sjoin, predicates, sjoin_nearest and point in polygon

A practical guide to spatial joins in GeoPandas with real Greater Manchester data: 13,187 NaPTAN bus stops, 1,386 OpenStreetMap schools, 215 ONS wards and 1,702 LSOAs. Covers point in polygon with sjoin, predicates, counts per polygon, how='left'/'inner'/'right', sjoin_nearest with max_distance, clip and overlay, and a timing comparison of a naive loop against the spatial index.

Beginner 12 min read

Tutorial Python

Zonal statistics in Python: exactextract vs rasterstats, with partial pixels, land-cover fractions and a benchmark

Calculate zonal statistics in Python with exactextract and rasterstats on real data: ONS 2021 LSOA boundaries for Cumbria with GHSL population, the Copernicus DEM and ESA WorldCover. Covers partial-pixel weighting vs pixel centroids, CRS alignment, categorical land-cover fractions, a speed benchmark, GeoPackage export and choropleth maps.

Intermediate 14 min read