ipdwInterp: Inverse Distance Weighting with custom distances

In ipdw: Spatial Interpolation by Inverse Path Distance Weighting

Inverse Distance Weighting with custom distances

Description

This function takes a rasterstack of pathdistances and generates surfaces by weighting parameter values by these distances

Usage

ipdwInterp(
  sf_ob,
  rstack,
  paramlist,
  overlapped = FALSE,
  yearmon = "default",
  removefile = TRUE,
  dist_power = 1,
  trim_rstack = FALSE
)

Arguments

sf_ob	sf object with point geometries
rstack	RasterStack of path distances
paramlist	character. String representing parameter names
overlapped	logical. Default is FALSE, specify TRUE if some points lie on top of barriers
yearmon	character. String specifying the name of the sf object
removefile	logical. Remove files after processing?
dist_power	numeric. Distance decay power (p)
trim_rstack	logical. Trim the raster stack by the convex hull of sf_ob

Details

Under the hood, this function evaluates:

V = \frac{∑\limits_{i=1}^n v_i \frac{1}{d_i^p}}{∑\limits_{i=1}^n \frac{1}{d_i^p}}

where d is the distance between prediction and measurement points, v_i is the measured parameter value, and p is a power parameter.

Value

RasterLayer

Examples

library(sf)
sf_ob <- data.frame(rnorm(2))
xy    <- data.frame(x = c(4, 2), y = c(8, 4))
sf_ob <- st_as_sf(cbind(sf_ob, xy), coords = c("x", "y"))

m <- matrix(NA, 10, 10)
costras <- raster(m, xmn = 0, xmx = ncol(m), ymn = 0, ymx = nrow(m))

# introduce spatial gradient
costras[] <- runif(ncell(costras), min = 1, max = 10)
for (i in 1:nrow(costras)) {
  costras[i, ] <- costras[i, ] + i
  costras[, i] <- costras[, i] + i
}

rstack <- pathdistGen(sf_ob, costras, 100, progressbar = FALSE)
final.raster <- ipdwInterp(sf_ob, rstack, paramlist = c("rnorm.2."), overlapped = TRUE)
plot(final.raster)
plot(sf_ob, add = TRUE)

ipdw documentation built on Jan. 6, 2023, 1:19 a.m.