Convert an connectivity matrix to an edge list

Source: R/matrix_to_edge_list.R

Converts a connectivity matrix to an edge list. This function allows to create the same edge list as the one obtained with create_edge_list().

matrix_to_edge_list(x, all = FALSE)

Arguments

x

a matrix object. The connectivity matrix to be converted in an edge list.

all

a logical value. If FALSE (default), removes missing edges.

Value

A data.frame with two (or three) columns:

  • from: label of one of the two nodes of the edge

  • to: label of the other node of the edge

  • edge: 0 (no edge) or 1 (edge). This column is returned only if all = TRUE.

Examples

library("chessboard")

# Two-dimensional sampling ----
sites_infos <- expand.grid("transect" = 1:3, "quadrat" = 1:5)
sites_infos
#>    transect quadrat
#> 1         1       1
#> 2         2       1
#> 3         3       1
#> 4         1       2
#> 5         2       2
#> 6         3       2
#> 7         1       3
#> 8         2       3
#> 9         3       3
#> 10        1       4
#> 11        2       4
#> 12        3       4
#> 13        1       5
#> 14        2       5
#> 15        3       5

nodes <- create_node_labels(data     = sites_infos, 
                            transect = "transect", 
                            quadrat  = "quadrat")

edges <- create_edge_list(nodes, method = "pawn", directed = TRUE)

conn_matrix <- connectivity_matrix(edges)

# Convert back to edge list ----
new_edges <- matrix_to_edge_list(conn_matrix)
new_edges
#>    from  to edge
#> 1   1-1 1-2    1
#> 2   1-2 1-3    1
#> 3   1-3 1-4    1
#> 4   1-4 1-5    1
#> 5   2-1 2-2    1
#> 6   2-2 2-3    1
#> 7   2-3 2-4    1
#> 8   2-4 2-5    1
#> 9   3-1 3-2    1
#> 10  3-2 3-3    1
#> 11  3-3 3-4    1
#> 12  3-4 3-5    1

# Check ----
identical(edges, new_edges)
#> [1] FALSE