Clip a shapefile using a bounding area

Clips an area from a larger shapefile provided in sf or sp formats.

Usage

clip_shapefile(
  x,
  limits,
  proj.limits = 4326,
  simplify = FALSE,
  tol = 60,
  return.boundary = FALSE,
  extra.validate = FALSE
)

Arguments

x

Original shapefile to be clipped as a an sf or sp polygons object. Required. Must contain CRS information.

limits

The constraining area used to clip x. Required. Either a numeric vector of length 4 or a spatial object from the sf or sp packages. The first element of the numeric vector defines the minimum longitude, second element the maximum longitude, third element the minimum latitude and fourth element the maximum latitude of the bounding box. If a spatial object, it must contain CRS information. See details.

proj.limits

The CRS projection attributes for limits. Hence format accepted by st_crs will suffice but integers are the easiest. Defaults to decimal degrees.

simplify

Should the x geometry be simplified before clipping? Useful to make the function faster for large shape files. Uses st_simplify function.

tol

Numerical tolerance value to be used for simplification. See ?sf::st_simplfy.

return.boundary

Logical. If TRUE returns the clip boundary together with the shapefile.

extra.validate

Logical indicating whether x should be run through extra validation. Slows down the function but is necessary in some cases involving anti-meridian.

Value

Clipped spatial object. If return.boundary = TRUE, a list containing the shapefile together with the clip boundary.

Details

The function uses the st_intersection function to clip smaller polygons from larger ones. The clip area is constrained by either a numeric vector or a spatial object in the limits argument. Defining limits by a sf object gives greater freedom for the clip area as the area does not have to be rectangular.

See also

Other create shapefiles: geonorge_bathymetry(), raster_bathymetry(), vector_bathymetry()

Author

Mikko Vihtakari