clip_shapefile: Clip a shapefile using a bounding area

In ggOceanMaps: Plot Data on Oceanographic Maps using 'ggplot2'

Clip a shapefile using a bounding area

Description

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.

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.

Value

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

Author(s)

Mikko Vihtakari

See Also

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

ggOceanMaps documentation built on May 29, 2024, 5:36 a.m.