Calculate roads covariates

Prepared groads data is clipped with the buffer polygons of radius. The total length of the roads are calculated. Then the density of the roads is calculated by dividing the total length from the area of the buffer. terra::linearUnits() is used to convert the unit of length to meters.

Usage

calc_sedac_groads(
  from = NULL,
  locs = NULL,
  locs_id = NULL,
  radius = 1000,
  fun = "sum",
  geom = FALSE,
  ...
)

Arguments

from

SpatVector(1). Output of process_sedac_groads.

locs

data.frame, characater to file path, SpatVector, or sf object.

locs_id

character(1). Column within locations CSV file containing identifier for each unique coordinate location.

radius

integer(1). Circular buffer distance around site locations. (Default = 1000).

fun

function(1). Function used to summarize the length of roads within sites location buffer (Default is sum).

geom

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

...

Placeholders.

Value

a data.frame or SpatVector object

Note

Unit is km / sq km. The returned data.frame object contains a $time column to represent the temporal range covered by the dataset. For more information, see https://sedac.ciesin.columbia.edu/data/set/groads-global-roads-open-access-v1/metadata.

See also

process_sedac_groads

Author

Insang Song

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_sedac_groads(
  from = groads, # derived from process_sedac_groads() example
  locs = loc,
  locs_id = "id",
  radius = 1000,
  fun = "sum",
  geom = FALSE
)
} # }