sv function

Semi-variogram computation

Compute the empirical semivariogram for a data set with specified x and y spatial coordinates and residuals.

sv(data, xcoordcol, ycoordcol, residcol, bins = 15, cutoff = NULL, ...)

Arguments

• data: A data frame or tibble that contains variables for the x coordinates, y coordinates, and residuals.
• xcoordcol: is the name of the column in the data frame with x coordinates or longitudinal coordinates
• ycoordcol: is the name of the column in the data frame with y coordinates or latitudinal coordinates
• residcol: is the name of the column in the data frame with residuals.
• bins: Number of equally spaced semivariogram bins. The default is 15.
• cutoff: The maximum spatial distance to be considered. The default is half of the maximum observed distance in the data frame.
• ...: Additional arguments to be used by stats::dist() for spatial distance calculations.

Returns

A data frame with the average distance in each bin (dist), the semivariance (gamma), and the number of unique pairs in each bin (np)

Examples

data(exampledataset) ## load a toy data set
slmobj <- slmfit(formula = counts ~ pred1 + pred2, data = exampledataset,
xcoordcol = 'xcoords', ycoordcol = 'ycoords', areacol = 'areavar')
sampleddataset <- na.omit(exampledataset)
svexample <- data.frame(
  xcoords = sampleddataset$xcoords,
  ycoords = sampleddataset$ycoords,
  resids = residuals(slmobj)
)
svdata <- sv(svexample, "xcoords", "ycoords", "resids")