The clean_network operator can be used used for cleaning and optimizing road networks. It helps deal with issues in GIS data such as disconnected segments, overlapping roads, and imprecise geometry.

clean_network(
    list<geometry> geometries,
    float tolerance,
    bool split_lines,
    bool keepMainConnectedComponent
)

• What it is: Collection of geometries (usually road segments) to clean
• How to get it: road collect each.shape or road_shapefile.contents
• Example:

list<geometry> road_geometries <- road collect each.shape;
list<geometry> road_geometries <- road_shapefile.contents;

• What it is: Maximum distance between points to be considered for merging
• Recommended values:
  • Small networks: 0.1 to 1.0 (e.g., urban network)
  • Large networks: 1.0 to 5.0 (e.g., rural network, highway network)
• Effects:
  • Lower values (e.g., 0.1): More precise, less merging
  • Higher values (e.g., 5.0): More aggressive merging
• Example scenarios:
  • For precise road networks: tolerance <- 0.5
  • For rough networks: tolerance <- 2.0

• What it is: Whether to split roads at intersection points
• Values:
  • true: Split roads at intersections (recommended for navigation)
  • false: Keep roads as continuous lines
• When to use:
  • true: For routing and navigation purposes
  • false: For visualization or analysis only

• What it is: Whether to keep only the main connected network
• Values:
  • true: Remove isolated road segments
  • false: Keep all road segments
• When to use:
  • true: For ensuring network connectivity
  • false: When isolated segments are important

// Basic cleaning with default values
list<geometry> clean_lines <- clean_network(
    road collect each.shape,
    1.0,    // moderate tolerance
    true,   // split at intersections
    true    // keep only main network 
);

global {
  // Network cleaning parameters
  float tolerance <- 1.0;
  bool split_lines <- true;
  bool keep_main_connected <- true;

    init {
        // Create initial roads
        create road from: road_shapefile;
        
        // Clean the network
        list<geometry> clean_lines <- clean_network(
            road collect each.shape,
            tolerance,
            split_lines,
            keep_main_connected
        );
        
        // Remove old roads
        ask road {
            do die;
        }
        
        // Create new roads
        loop clean_geom over: clean_lines {
            create road {
                shape <- clean_geom;
            }
        }
        
        // Create network graph
        road_network <- as_edge_graph(road);
    }
}