Internal function to calculate Manhattan distance (L1 norm) between coordinates, adapted for geographic coordinate systems.
calculate_manhattan_distance(lon1, lat1, lon2, lat2, unit)List with minimum distance and corresponding index.
Origin longitude.
Origin latitude.
Destination longitude vector.
Destination latitude vector.
Distance unit: "nm" or "km".
The Manhattan distance calculates the sum of absolute differences between coordinates, adapted for geographic coordinates using spherical projection approximations. This implementation accounts for Earth's curvature by applying latitude corrections to longitude differences.