| anyNA.sk | Check for presence of grid points with missing data (NAs) | 
| as.double.sk | Coerce grid values to numeric (double type) | 
| as.integer.sk | Coerce grid values to integer | 
| as.logical.sk | Coerce grid values to logical | 
| as.matrix.sk | convert to matrix | 
| as.vector.sk | Convert grid data to vector of specified mode | 
| dim.sk | Grid dimensions | 
| is.na.sk | Indices of grid points with missing data (NAs) | 
| length.sk | The number of grid-points | 
| Math.sk | Math group generics | 
| mean.sk | Calculate the mean value in a grid | 
| Ops.sk | Operations group generics | 
| plot.sk | Heatmap plots | 
| print.sk | Auto-printing | 
| sk | Make a snapKrig grid list object | 
| sk_cmean | Compute kriging predictor (or variance) for an sk grid | 
| sk_coords | Return coordinates of a grid of points in column-vectorized order | 
| sk_export | Convert "sk" grid to SpatRaster | 
| sk_fit | Fit a covariance model to an sk grid by maximum likelihood | 
| sk_GLS | Generalized least squares (GLS) with Kronecker covariances for sk grids | 
| sk_LL | Likelihood of covariance model 'pars' given the data in sk grid 'g' | 
| sk_nLL | Negative log-likelihood for parameter vector 'p' | 
| sk_pars | Initialize Kronecker covariance function parameters for a sk grid | 
| sk_plot | Plot grid data | 
| sk_plot_pars | Plot the covariance structure of a snapKrig model | 
| sk_plot_semi | Plot a semi-variogram | 
| sk_rescale | Up or down-scale a sk grid by an integer factor | 
| sk_sample_vg | Sample point pair absolute differences for use in semi-variogram estimation | 
| sk_sim | Random draw from multivariate normal distribution for sk grids | 
| sk_snap | Snap a set of points to a "sk" grid | 
| sk_var | Generate a covariance matrix or its factorization | 
| summary.sk | Grid summary | 
| [.sk | Extract a sk list element (single-bracket access) | 
| [<-.sk | Single-bracket assign | 
| [[.sk<- | sk_methods.R Dean Koch, 2022 S3 methods for sk grid list objects |