Create a distance matrix between nodes for spatial models

Calculate the euclidian distances beween coordinates for all coordinates within the cutoff.

Usage

distance_matrix(x, y, cutoff, min_dist = NULL, na_fail = TRUE)

Arguments

x

Projected x coordinate

y

Projected y coordinate

cutoff

The distance cutoff

min_dist

The minimum distance to separate two nodes. If the coordinates for two nodes are identical, the min_dist must be assigned or an error is raised. Default is NULL, i.e., to raise an error.

na_fail

A logical indicating whether missing values in x or y should raise an error or assign zero to all distances involving missing values. Default is TRUE, i.e., to raise an error.

Value

dgCMatrix

Examples

## Generate a grid 10 x 10 and place one node in each cell
## separated by 100m.
nodes <- expand.grid(x = (0:9) * 100, y = (0:9) * 100)
plot(y ~ x, nodes)


## Define the cutoff to only include neighbors within 300m.
d <- distance_matrix(x = nodes$x, y = nodes$y, cutoff = 300)

## View the first 10 rows and columns in the distance matrix
d[1:10, 1:10]
#> 10 x 10 sparse Matrix of class "dgCMatrix"
#>                                              
#>  [1,]   . 100 200 300   .   .   .   .   .   .
#>  [2,] 100   . 100 200 300   .   .   .   .   .
#>  [3,] 200 100   . 100 200 300   .   .   .   .
#>  [4,] 300 200 100   . 100 200 300   .   .   .
#>  [5,]   . 300 200 100   . 100 200 300   .   .
#>  [6,]   .   . 300 200 100   . 100 200 300   .
#>  [7,]   .   .   . 300 200 100   . 100 200 300
#>  [8,]   .   .   .   . 300 200 100   . 100 200
#>  [9,]   .   .   .   .   . 300 200 100   . 100
#> [10,]   .   .   .   .   .   . 300 200 100   .