Filtering & Grouping

GeoGrids.jl provides powerful functionality for filtering points based on geographical regions. This includes both basic point-in-region testing and efficient filtering of large point sets.

Basic Filtering

The filter_points function provides a straightforward way to filter points based on regions:

# Create a latitude belt region
region = LatBeltRegion(lim=(-10,10))
points = icogrid(sepAng=4)

# Filter points to only those in the region
filtered = filter_points(points, region)
plot = plot_geo_points(filtered; title="Points Filtered to Equatorial Belt")
to_documenter(plot) # hide

Fast Filtering

For large point sets, GeoGrids.jl provides optimized filtering through filter_points_fast:

# Create a polygon region
region = PolyRegion(domain=[
    LatLon(10°, -5°), 
    LatLon(10°, 15°), 
    LatLon(27°, 15°), 
    LatLon(27°, -5°)
])
points = rectgrid(1)[:]  # Dense grid
filtered = filter_points_fast(points, region)

Grouping Points by Region

Sometimes you need to categorize points based on which regions they fall into. The group_by_domain function handles this:

# Create multiple regions
regions = [
    GeoRegion(admin="Spain"),
    GeoRegion(admin="France"),
    GeoRegion(admin="Italy")
]
points = icogrid(sepAng=2)

# Group points by region
grouped = group_by_domain(points, regions)

# Plot points in Spain as an example
spain_points = grouped["Spain"]
plot = plot_geo_points(spain_points; title="Points Grouped to Spain")