edge.creation: Creating graph edges

In FMestre1/gDefrag: Graph-Based Landscape De-Fragmentation

Creating graph edges

Description

Generates the graph edges, connecting nodes that are the landscape polygons resulting from the landscape clip by the road network.

Usage

edge.creation(nodes, land_polyg, min_length = 0, 
min_pol_area = 0, plot = TRUE, shape = FALSE, 
shape_name_edges = "shape_edges")

Arguments

nodes	Output of the function node.creation.
land_polyg	SpatialPolygonsDataFrame loaded with readOGR function of the package rgdal (polygon shapefile).
min_length	Minimum length of the road segment to consider creating an edge representing it.
min_pol_area	Minimum area for a given polygon to be considered a node.
plot	Plot after running? (TRUE/FALSE).
shape	Create a shapefile with the edges (TRUE/FALSE).
shape_name_edges	Name of the edges shapefile to be created (without prioritization).
overwrite	Should the shapefile file be overwritten?

Details

If shape = TRUE, this function produces one shapefile with edges without prioritization metrics.

Value

The function returns a SpatVector with the edges. The data table of this data frame has the following fields:

• node_A - Node A Id.

• node_B - Node B Id.

• distance - Euclidean distance between nodes A and B (edge length).

• x_node_A - Node A longitude.

• y_node_A - Node A latitude.

• x_node_B - Node B longitude.

• y_node_A - Node A latitude.

• raster_value_A - Average value of the underlying raster in the polygon represented by node A.

• raster_value_B - Average value of the underlying raster in the polygon represented by node B.

• road_ID - Id of the road represented by the edge.

• road_length - Length of the road represented by the edge.

Author(s)

Frederico Mestre, Fernando Ascensao and A. Marcia Barbosa

See Also

node.creation

Examples

data(road_P)

#Obtaining nodes
out1 <- node.creation(land_polyg = road_P, 
                      value_col = "frst_sm",
                      scale_nodes = 10, 
                      cex_labels = 1, 
                      shape = TRUE,
                      shape_name_nodes = "shape_nodes_file", 
                      overwrite = TRUE)

#Obtaining edges
out2 <- edge.creation(nodes = out1, 
                      land_polyg = road_P,
                      min_length = 0, 
                      min_pol_area = 0, 
                      shape_name_edges = "shape_edges_file",
                      shape = TRUE,
                      overwrite = TRUE)

FMestre1/gDefrag documentation built on June 11, 2025, 1:32 a.m.