Determines which administrative areas contain the given points

Usage

getAreaName(
  pts,
  shapefile,
  areaNameVar = "NAME_1",
  delta = 0.05,
  mean.neighbor = 50,
  max.bytes = 3 * 2^30
)

Arguments

pts: 2 column matrix of lon/lat coordinates
shapefile: A SpatialPolygonsDataFrame object
areaNameVar: The column name in slot(shapefile, "data") corresponding to the area level of interest
delta: Argument passed to fields::fields.rdist.near in fields package
mean.neighbor: Argument passed to fields::fields.rdist.near in fields package
max.bytes: Maximum allowed memory in bytes (default is 3Gb). Determines whether to call fields::fields.rdist.near which saves memory but requires delta and mean.neighbor inputs to be specified for fields::fields.rdist.near

Value

A list of area IDs, area names, whether or not points are in multiple areas, and whether or not points are in no areas and assigned to the nearest one.

Details

For any points not in an area, they are assigned the nearest area using fields::fields.rdist.near or fields::rdist depending on the number of points and the maximum memory in bytes with a warning.

delta and mean.neighbor arguments only used when some points are not in areas, perhaps due to inconsistencies in shapefiles.

Author

John Paige

Examples

if (FALSE) { # \dontrun{
# download Kenya GADM shapefiles from SUMMERdata github repository
githubURL <- "https://github.com/paigejo/SUMMERdata/blob/main/data/kenyaMaps.rda?raw=true"
download.file(githubURL,"kenyaMaps.rda")

# load it in
load("kenyaMaps.rda")

# use the shapefile data to see what Admin1 and 2 areas the 
# points (0, 37) and (0.5, 38) are in
# (these are longitude/latitude coordinates)
pts = cbind(c(37, 38), c(0, .5))
head(slot(adm1, "data"))
admin1Areas = getAreaName(pts, adm1, "NAME_1")
admin2Areas = getAreaName(pts, adm2, "NAME_2")
} # }