Determines whether given positions are near land based on a coastline shape file.
The Natural Earth 1:50m land vectors are included as default shapefile in iRfcb.
Usage
ifcb_is_near_land(
latitudes,
longitudes,
distance = 500,
shape = NULL,
crs = 4326,
utm_zone = 33,
remove_small_islands = TRUE,
small_island_threshold = 2e+06
)Arguments
- latitudes
Numeric vector of latitudes for positions.
- longitudes
Numeric vector of longitudes for positions.
- distance
Buffer distance in meters around the coastline. Default is 500 m.
- shape
Optional path to a shapefile containing coastline data. If provided, the function will use this shapefile instead of the default Natural Earth 1:50m land vectors. Using a more detailed shapefile allows for a smaller buffer distance. For detailed European coastlines, download polygons from the EEA at https://www.eea.europa.eu/data-and-maps/data/eea-coastline-for-analysis-2/gis-data/eea-coastline-polygon. For more detailed world maps, download from Natural Earth at https://www.naturalearthdata.com/downloads/10m-physical-vectors/.
- crs
Coordinate reference system (CRS) to use for positions and output. Default is EPSG code 4326 (WGS84).
- utm_zone
UTM zone for buffering the coastline. Default is 33 (between 12°E and 18°E, northern hemisphere).
- remove_small_islands
Logical indicating whether to remove small islands from the coastline if a custom shapefile is provided. Default is TRUE.
- small_island_threshold
Area threshold in square meters below which islands will be considered small and removed, if remove_small_islands is set to TRUE. Default is 2 sqkm.
Details
This function calculates a buffered area around the coastline and checks if given positions (specified by longitudes and latitudes) are within this buffer or intersect with land.
Examples
# Define coordinates
latitudes <- c(62.500353, 58.964498, 57.638725, 56.575338)
longitudes <- c(17.845993, 20.394418, 18.284523, 16.227174)
# Call the function
near_land <- ifcb_is_near_land(latitudes, longitudes, distance = 300, crs = 4326)
# Print the result
print(near_land)
#> [1] FALSE FALSE TRUE FALSE