latlong2region: Match coordinates to regions in a shapefile.

In walshc/latlong2region: latlong2region

Description

Match coordinates to regions in a shapefile. Also includes the possibility to find the region a point is closest to if, for example, the point is the water.

Usage

latlong2region(p, shp, closest = TRUE)

Arguments

p	Longitudes and latitudes of points. Can be a vector of two points or a matrix or data.frame of 2 columns (first is longitude, second is latitude). Can also be a SpatialPoints object.
shp	The SpatialPolygonDataFrame to match to.
closest	Whether to find the closest region for points that don't fall in any region in shp. Default is TRUE. This step can be slow for large shapefiles.

Value

Returns a data.frame with p and the corresponding elements in shp.

Examples

  # Download, extract and load the US counties shapefile:
  us <- "http://www2.census.gov/geo/tiger/GENZ2015/shp/cb_2015_us_county_500k.zip"
  download.file(us, "us_counties.zip")
  unzip("us_counties.zip")
  shp <- rgdal::readOGR(".", "cb_2015_us_county_500k")

  # Points to use, the Chicago point is in Lake Michigan so it won't be matched.
  # It will be matched to the closest county.
  df <- data.frame(name = c("New York", "San Francisco", "Chicago"),
                   lon  = c(-74.00594, -122.41942, -87.61),
                   lat  = c(40.71278, 37.77493, 41.87811))

  p <- df[, c("lon", "lat")]
  latlong2region(p, shp)

walshc/latlong2region documentation built on Jan. 1, 2022, 7:50 a.m.