RooksNeighFind {ICvectorfields}

Classify Rook's Neighbours Comprising Spread Patterns in Vector Fields

Description

After running the PatternDetect function, this function enables classification of neighbour cells. Because the pattern detect function classifies central cells according to the patterns of vector direction in their Rook's neighbourhood, the neighbouring grid locations that comprise the pattern are not labeled. This is remedied by the RooksNeighFind function which classifies neighbour cells around focal grids classified with one of the four patterns that the PatternDetect function is able to recognize. The function returns a data frame similar to the input data frame with a column appended. In the appended column, neighbours surrounding focal cells labeled with a particular pattern will be labeled as follows: neighbours of the divergence pattern are labeled with a one, neighbours of the convergence pattern are labeled with a two, neighbours of the partial divergence pattern are labeled with a three, and neighbours of the partial convergence pattern are labeled with a four. In cases where neighbours are shared, the priority order from lowest to highest is four for partial convergence to one for divergence. Thus, a neighbour that is shared between a focal grid classified as a convergence and a nearby focal grid classified as a divergence will be labeled with a one instead of a two.

Usage

RooksNeighFind(vfdf)

Arguments

vfdf

A data frame as returned by PatternDetect

Value

A data frame similar to vfdf except that it includes an additional column called NeighType as described above.

Examples

# creating convergence/divergence patterns
Mat1 <- matrix(rep(0,9*9), nrow = 9)
Mat1[3, c(4, 6)] <- 1
Mat1[7, c(4, 6)] <- 1
Mat1[c(4, 6), 3] <- 1
Mat1[c(4, 6), 7] <- 1
Mat1

Mat2 <- matrix(rep(0,9*9), nrow = 9)
Mat2[2, c(4, 6)] <- 1
Mat2[8, c(4, 6)] <- 1
Mat2[c(4, 6), 2] <- 1
Mat2[c(4, 6), 8] <- 1
Mat2

# rasterizing
rast1 <- terra::rast(Mat1)
terra::plot(rast1)
rast2 <- terra::rast(Mat2)
terra::plot(rast2)

# Detecting a divergence
(VFdf1 <- DispField(rast1, rast2, factv1 = 3, facth1 = 3, restricted = TRUE))
(patdf1 <- PatternDetect(VFdf1))
(neighdf1 <- RooksNeighFind(patdf1))
# Rook's neighbour grids are labeled with a one.

# Detecting a convergence
(VFdf2 <- DispField(rast2, rast1, factv1 = 3, facth1 = 3, restricted = TRUE))
(patdf2 <- PatternDetect(VFdf2))
(neighdf2 <- RooksNeighFind(patdf2))
# Rook's neighbour grids are labeled with a two.