catSpatInterp: Categorical Spatial Interpolation

In swfscMisc: Miscellaneous Functions for Southwest Fisheries Science Center

Categorical Spatial Interpolation

Description

Create a raster of probability of categorical values interpolated across a 2-dimensional space given a set of points where each is assigned to one of several classes.

Usage

catSpatInterp(
  data,
  x.col = "x",
  y.col = "y",
  group.col = "group",
  num.grid = 100,
  knn = 10,
  hull.buffer = 0.1,
  num.cores = 1,
  num.batches = NULL
)

Arguments

data	matrix or data.frame containing points and grouping designation.
x.col, y.col, group.col	numbers or characters identifying which columns in data are the x and y values and grouping designation.
num.grid	number of grid cells for k-nearest neighbor interpolation.
knn	number of nearest neighbors to consider for interpolation.
hull.buffer	percent increase of convex hull to use as spatial area to interpolate over.
num.cores	number of cores to distribute interpolations over.
num.batches	number of batches to divide grid cell interpolations into.

Value

A list containing a raster and points of buffered convex hull.

Author(s)

Eric Archer [e-mail]

References

Adapted from code originally presented in a blog post on Categorical Spatial Interpolation by Timo Grossenbacher https://timogrossenbacher.ch/2018/03/categorical-spatial-interpolation-with-r/

Examples

## Not run: 
iris.mds <- stats::cmdscale(dist(iris[, 1:4]), k = 2)
mds.df <- setNames(
  cbind(iris.mds, data.frame(iris$Species)),
  c("dim1", "dim2", "Species")
)

result <- catSpatInterp(
  mds.df, x.col = "dim1", y.col = "dim2", group.col = "Species", 
  num.grid = 300, knn = 20, hull.buffer = 0.05,
  num.cores = 5, num.batches = NULL
)

library(ggplot2)
ggplot(mapping = aes(dim1, dim2)) +
  geom_raster(
    aes(fill = Species, alpha = prob), 
    data = result$raster
  ) +
  geom_polygon(data = result$hull.poly, fill = NA, col = "black") +
  geom_hline(yintercept = 0, col = "white") +
  geom_vline(xintercept = 0, col = "white") +
  geom_point(
    aes(fill = Species), 
    data = mds.df, 
    col = "black", 
    shape = 21, 
    size = 4
  ) + 
  theme(
    axis.ticks = element_blank(),
    axis.text = element_blank(),
    axis.title = element_blank(),
    legend.position = "top",
    panel.grid = element_blank(),
    panel.background = element_blank()
  )

## End(Not run)

swfscMisc documentation built on Sept. 8, 2023, 5:55 p.m.