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Summary statistics for a windshed

ws_summarize.Rd

A "windshed" is a raster layer representing upwind or downwind connectivity for a given point. This function computes a range of statistics summarizing a windshed, such as the size, centroid location, and isotropy of the wind accessibility surface. It is useful primarily for comparing the windshed properties of multiple different sites.

Usage

ws_summarize(x, origin, radius = NULL)

Arguments

x

SpatRaster representing wind accessibility, with higher values indicating greater accessibility. (For example, this could be the output of `random_walk()`, or `least_cost_surface(..., rate = TRUE)`.)

origin

Coordinates of center point (matrix with 2 columns and 1 row).

radius

Optional windshed radius, in km; cells farther from the origin than this will be excluded from the summary statistics.

Value

A named vector of summary statistics:

  • "centroid_x": Longitude of windshed "centroid". The centroid is the mean of all lon-lat coordinates, weighed by the wind accessibility values in x.

  • "centroid_y": Latitude of windshed centroid.

  • "centroid_distance": Distance from origin to windshed centroid, in km.

  • "centroid_bearing": Bearing from origin to windshed centroid, in degrees.

  • "windshed_distance: Mean distance from origin, in km. This is the average distance from the origin to every grid cell, weighted by accessibility.

  • "windshed_bearing": Mean bearing from origin, in degrees. This is the circular-mean bearing from the origin to every other grid cell, weighted by accessibility.

  • "windshed_isotropy": Circular standard deviation of the bearing from the origin to every other grid cell, weighted by accessibility. Low values indicate that accessible sites are concentrated in a narrow range of compass directions, while high values indicate a wide distribution of directions. The range of possible values is 0-1.

  • "windshed_size": Mean accessibility. This is the average of all accessibility values, weighted to correct for grid distortions. Higher values indicate landscapes with greater overall wind accessibility.

  • "windshed_landarea": A realative measure of the land area covered by grid cells with nonzero wind accessibility.