Calculate land cover covariates

Compute ratio of land cover class in circle buffers around points. Returns a data.frame object containing locs_id, longitude, latitude, time (year), and computed ratio for each land cover class.

Usage

calc_nlcd(
  from,
  locs,
  locs_id = "site_id",
  mode = c("exact", "terra"),
  radius = 1000,
  max_cells = 5e+07,
  geom = FALSE,
  nthreads = 1L,
  ...
)

Arguments

from

SpatRaster(1). Output of process_nlcd().

locs

terra::SpatVector of points geometry

locs_id

character(1). Unique identifier of locations

mode

character(1). One of "exact" (using exactextractr::exact_extract()) or "terra" (using terra::freq()).

radius

numeric (non-negative) giving the radius of buffer around points

max_cells

integer(1). Maximum number of cells to be read at once. Higher values may expedite processing, but will increase memory usage. Maximum possible value is 2^31 - 1. Only valid when mode = "exact". See exactextractr::exact_extract for details.

geom

logical(1). Should the function return a SpatVector? Default is FALSE. The coordinate reference system of the SpatVector is that of from.

nthreads

integer(1). Number of threads to be used

...

Placeholders.

Value

a data.frame or SpatVector object

Note

NLCD is available in U.S. only. Users should be aware of the spatial extent of the data. The results are different depending on mode argument. The "terra" mode is less memory intensive but less accurate because it counts the number of cells intersecting with the buffer. The "exact" may be more accurate but uses more memory as it will account for the partial overlap with the buffer.

See also

process_nlcd

Examples

## NOTE: Example is wrapped in `\dontrun{}` as function requires a large
##       amount of data which is not included in the package.
if (FALSE) { # \dontrun{
loc <- data.frame(id = "001", lon = -78.90, lat = 35.97)
calc_nlcd(
  from = nlcd, # derived from process_nlcd() example
  locs = loc,
  locs_id = "id",
  mode = "exact",
  geom = FALSE
)
} # }