regkrige {mapsRinteractive}

regkrige

Description

Regression kriging using a standardized variogram.

Usage

regkrige(
  x = NULL,
  y = NULL,
  z = NULL,
  field = NULL,
  edge = 0,
  filter = 1,
  resolution = NULL,
  md = "Sph",
  rg = NULL,
  ng = 0.1,
  check.data = TRUE,
  cross.validate = TRUE
)

Arguments

x

SpatRaster. Required. Must be have a defined Cartesian coordinate system. Data must be continuous. If more than one layer, the first layer will be used.

y

SpatVector of polygons. Optional. Delineates the area within which the raster layer shall be locally adapted and evaluated. If not provided, the analyses will be performed within the intersect of the raster and the sampled area. Must be have a defined Cartesian coordinate system (same as x).

z

SpatVector of points Required. Must have at least one column with numerical data and these data must be of the same entity and unit as x (specify this column by argument: field). Must be have a defined Cartesian coordinate system (same as x).

field

Character value. Required. Name of the column in y with the data that shall be used to locally adapt and evaluate the raster.

edge

Numeric value. Optional. Specifies the width (unit of the coordinate reference system) of a buffer zone inside the edge of the polygon that is excluded from the analyses. Allowed values are within the closed range of 0-10000.

filter

Positive integer. Optional. No of cells in the side of a square window for mean filtering of x. Filtering is done before any resampling (see argument: resolution). Allowed values are within the closed range of 1-20.

resolution

Positive numeric value. Optional. The resolution (m) to which the imported raster shall be resampled before the adaptation. Allowed values are within the closed range of 0.1-10000. In addition, a resolution that means more than 1E+8 raster cells is not allowed.

md

Character value. Optional. Variogram model type for the standardized variograms used for ordinary kriging interpolation of observed data or residuals. Variograms are generated by gstat::vgm. Default is "Sph" (spherical model).

rg

Numeric value. Optional. Range of the standardized variograms used for ordinary kriging interpolation of observed data or residuals. Variograms are generated by gstat::vgm. If no rg is specified it will be set to half of the square root of the mapping area: y (possibly shrinked by edge).

ng

Numeric value. Optional. Nugget of the standardized variograms used for ordinary kriging interpolation of observed data or residuals. Variograms are generated by gstat::vgm. The nugget is expressed as a fraction of the sill. A ng = 0.1 means that the nugget is 10 percent of the sill. The sill is by default equal to the variance of the data to be kriged (i.e the point observations or the residuals). Allowed values of ng are within the closed range of 0-1.

check.data

Logical value. Default is TRUE. Shall attributes, geometries and projections of the input data (arguments x, y and z) be checked.

cross.validate

Logical value. If TRUE, a leave-one-out cross-validation is performed

Details

This is the ordinary kriging function called by the mri function. It uses a standardized semivariogram model and requires a raster template for which predictions are made. For details, see documentation of the mri function.

Value

A list with 1) a raster layer with predicted values and 2) if cross.validate=T, a SpatVector of points with predictions from a leave-one-out cross-validation. For details, see mri function.