RSR {ubms}

Get Information for a Restricted Spatial Regression Model

Description

A call to RSR in the formula for a state process adds an autocorrelated spatial random effect to the model in the form of a Restricted Spatial Regression (RSR). For examples of RSRs applied to ecological data, see Johnson et al. (2013) and Broms et al. (2014). The function can also be used outside a formula to visualize the spatial relationships between sites in your data and choose an appropriate distance threshold below which two sites will be considered neighbors, and thus potentially correlated, for the RSR model. For more details, see the example vignette: vignette("spatial-models", package = "ubms")

Usage

RSR(x, y = NULL, threshold, moran_cut = NULL, plot_site = NULL)

Arguments

x

A vector of coordinates (should be projected)

y

An (optional) second vector of coordinates

threshold

The distance cutoff below which two sites will be considered neighbors. Should be the same units as the coordinates.

moran_cut

The number of eigenvectors to use in the RSR. The possible range of values is between 1 and the number of sites. Smaller numbers will result in faster runtime and smoother map output, and vice-versa. If not provided (the default), the number of eigenvectors will be set as 10% of the number of sites which is usually appropriate.

plot_site

If a site number (as an integer) is supplied, the function returns a plot showing that site and its neighbors under the current settings. Useful for deciding what to set your threshold at.

Value

Either a list of spatial matrices used for the RSR (only useful internally to ubms), or if plot_site is an integer, a ggplot object.

References

Broms KM, Johnson DS, Altwegg R, Conquest LL. 2014. Spatial occupancy models applied to atlas data show Southern Ground Hornbills strongly depend on protected areas. Ecological Applications 24: 363-374.

Johnson DS, Conn PB, Hooten MB, Ray JC, Pond BA. 2013. Spatial occupancy models for large data sets. Ecology 94: 801-808.

Examples

# Generate some coordinates
x <- runif(100,0,10)
y <- runif(100,0,10)
# Show neighbors of site 10 when threshold is 3 units
RSR(x, y, threshold=3, plot_site=10)