point2poly_krige {SUNGEO}

Point-to-polygon interpolation, ordinary and universal Kriging method

Description

Function for interpolating values from a source points layer to an overlapping destination polygon layer, using ordinary and universal kriging with automatic variogram fitting

Usage

point2poly_krige(
  pointz,
  polyz,
  rasterz = NULL,
  yvarz = NULL,
  xvarz = NULL,
  pycno_yvarz = NULL,
  funz = base::mean,
  use_grid = FALSE,
  nz_grid = 25,
  blockz = 0,
  pointz_x_coord = NULL,
  pointz_y_coord = NULL,
  polyz_x_coord = NULL,
  polyz_y_coord = NULL,
  messagez = ""
)

Arguments

pointz

Source points layer. sf, sp, or data frame object.

polyz

Destination polygon layer. Must have identical CRS to pointz. sf, sp, or data frame object.

rasterz

Source raster layer (or list of raster), with covariate(s) used for universal kriging. Must have identical CRS to polyz. RasterLayer object or list of RasterLayer objects.

yvarz

Names of numeric variable(s) to be interpolated from source points layer to destination polygons. Character string or vector of character strings.

xvarz

Names of numeric variable(s) for universal Kriging, in which yvarz is linearly dependent. Character string or vector of character strings.

pycno_yvarz

Names of spatially extensive numeric variables for which the pycnophylactic (mass-preserving) property should be preserved. Must be a subset of yvarz. Character string or vector of character strings.

funz

Aggregation function to be applied to values in rasterz and to interpolated values. Must take as an input a vector x. Default is mean. Function.

use_grid

Use regular grid as destination layer for interpolation, before aggregating to polygons? Default is FALSE.

nz_grid

Number of grid cells in x and y direction (columns, rows). Integer of length 1 or 2. Default is 25. Ignored if use_grid=FALSE.

blockz

Size of blocks used for Block Kriging, in meters. Integer of length 1 or 2. Default is 0.

pointz_x_coord

Name of numeric variable corresponding to a measure of longitude (Easting) in a data frame object for pointz. Character string.

pointz_y_coord

Name of numeric variable corresponding to a measure of Latitude (Northing) in a data frame object for pointz. Character string.

polyz_x_coord

Name of numeric variable corresponding to a measure of longitude (Easting) in a data frame object for polyz. Character string.

polyz_y_coord

Name of numeric variable corresponding to a measure of Latitude (Northing) in a data frame object for polyz. Character string.

messagez

Optional message to be printed during Kriging estimation. Character string.

Details

This function performs Ordinary and Universal Kriging, automatically selecting a variogram model with the smallest residual sum of squares from the sample variogram. See autofitVariogram.

Unlike other available point-to-polygon interpolation techniques, this function currently only accepts numeric variables in varz and does not support interpolation of character strings.

Value

sf polygon object, with variables from pointz interpolated to the geometries of polyz.

Examples

# Ordinary Kriging with one variable
## Not run: 
data(clea_deu2009)
data(clea_deu2009_pt)
out_1 <- point2poly_krige(pointz = clea_deu2009_pt,
                         polyz = clea_deu2009,
                         yvarz = "to1")
par(mfrow=c(1,2))
plot(clea_deu2009["to1"], key.pos = NULL, reset = FALSE)
plot(out_1["to1.pred"], key.pos = NULL, reset = FALSE)

## End(Not run)

# Ordinary Kriging with multiple variables
## Not run: 
out_2 <- point2poly_krige(pointz = clea_deu2009_pt,
                         polyz = clea_deu2009,
                         yvarz = c("to1","pvs1_margin"))
par(mfrow=c(1,2))
plot(clea_deu2009["pvs1_margin"], key.pos = NULL, reset = FALSE)
plot(out_2["pvs1_margin.pred"], key.pos = NULL, reset = FALSE)

## End(Not run)

# Universal Kriging with one variable from a raster
## Not run: 
data(gpw4_deu2010)
data(clea_deu2009)
data(clea_deu2009_pt)
out_3 <- point2poly_krige(pointz = clea_deu2009_pt,
                         polyz = clea_deu2009,
                         yvarz = "to1",
                         rasterz = gpw4_deu2010)
par(mfrow=c(1,2))
plot(clea_deu2009["to1"], key.pos = NULL, reset = FALSE)
plot(out_3["to1.pred"], key.pos = NULL, reset = FALSE)

## End(Not run)

# Block Kriging with block size of 100 km
## Not run: 
data(clea_deu2009)
data(clea_deu2009_pt)
out_4 <- point2poly_krige(pointz = clea_deu2009_pt,
                         polyz = clea_deu2009,
                         yvarz = "to1",
                         blockz = 100000)
par(mfrow=c(1,2))
plot(clea_deu2009["to1"], key.pos = NULL, reset = FALSE)
plot(out_4["to1.pred"], key.pos = NULL, reset = FALSE)

## End(Not run)