Join spatial data to points

Performs a spatial join to obtain geographic fields for specified lon/lat columns.

Usage

join_spatial(
  x,
  y,
  id_col,
  lon_col,
  lat_col,
  crs_lonlat = 4326,
  crs_equal_area = 5070,
  largest = FALSE
)

Arguments

x

A data.table of survey data

y

an sf object with the geometry of interest

id_col

character. The column in x that is a unique identifier

lon_col

character. The column in x that has longitude

lat_col

character. The column in x that has latitude

crs_lonlat

numeric. The EPSG code for lonlat data (defaults to WGS84)

crs_equal_area

numeric. The EPSG code for an equal area projection. Many spatial operations assume projected data (not lon/lat). Defaults to US Albers Equal Area

largest

logical. If TRUE, return x features with fields of y that have the largest overlap with each of the features of x; see st_join. This is useful if join is returning more than one value of y for each x.

Value

A data.table is returned with all columns from x plus all columns from y.

Author

Matt Landis

Examples

if (FALSE) {
x = data.table(id = 1:3, lon = c(-82.33, -79.17, -76.17), lat = c(35.50, 36.27, 36.49))
nc = st_read(system.file("shape/nc.shp", package = "sf"))[, c("FIPS", "NAME", "geometry")]
z = join_spatial(x, nc, id_col = "id", lon_col = "lon", lat_col = "lat")
z
}