ms_clip function

Remove features or portions of features that fall outside a clipping area.

Removes portions of the target layer that fall outside the clipping layer or bounding box.

ms_clip(target, clip = NULL, bbox = NULL, remove_slivers = FALSE, ...)

Arguments

• target: the target layer from which to remove portions. One of:

  • geo_json or character points, lines, or polygons;
  • SpatialPolygons, SpatialLines, SpatialPoints;
  • sf or sfc points, lines, or polygons object

• clip: the clipping layer (polygon). One of:

  • geo_json or character polygons;
  • SpatialPolygons*;
  • sf or sfc polygons object

• bbox: supply a bounding box instead of a clipping layer to extract from the target layer. Supply as a numeric vector: c(minX, minY, maxX, maxY).

• remove_slivers: Remove tiny sliver polygons created by clipping. (Default FALSE)

• ...: Arguments passed on to apply_mapshaper_commands

  • force_FC: should the output be forced to be a FeatureCollection (or sf object or Spatial*DataFrame) even if there are no attributes? Default TRUE. If FALSE and there are no attributes associated with the geometries, a GeometryCollection (or Spatial object with no dataframe, or sfc) will be output.
  • sys: Should the system mapshaper be used instead of the bundled mapshaper? Gives better performance on large files. Requires the mapshaper node package to be installed and on the PATH.
  • sys_mem: How much memory (in GB) should be allocated if using the system mapshaper (sys = TRUE)? Default 8. Ignored if sys = FALSE. This can also be set globally with the option "mapshaper.sys_mem"
  • quiet: If sys = TRUE, should the mapshaper messages be silenced? Default FALSE. This can also be set globally with the option "mapshaper.sys_quiet"

Returns

clipped target in the same class as the input target

Examples

if (rmapshaper:::check_v8_major_version() >= 6L) {
  library(geojsonsf, quietly = TRUE)
  library(sf)

  poly <- structure("{\"type\":\"FeatureCollection\",
    \"features\":[{\"type\":\"Feature\",\"properties\":{},
    \"geometry\":{\"type\":\"Polygon\",\"coordinates\":
    [[[52.8658,-44.7219],[53.7702,-40.4873],[55.3204,-37.5579],
    [56.2757,-37.917],[56.184,-40.6443],[61.0835,-40.7529],
    [58.0202,-43.634],[61.6699,-45.0678],[62.737,-46.2841],
    [55.7763,-46.2637],[54.9742,-49.1184],[52.799,-45.9386],
    [52.0329,-49.5677],[50.1747,-52.1814],[49.0098,-52.3641],
    [52.7068,-45.7639],[43.2278,-47.1908],[48.4755,-45.1388],
    [50.327,-43.5207],[48.0804,-41.2784],[49.6307,-40.6159],
    [52.8658,-44.7219]]]}}]}", class = c("geojson", "json"))
  poly <- geojson_sf(poly)
  plot(poly)

  clip_poly <- structure('{
  "type": "Feature",
  "properties": {},
  "geometry": {
  "type": "Polygon",
  "coordinates": [
  [
  [51, -40],
  [55, -40],
  [55, -45],
  [51, -45],
  [51, -40]
  ]
  ]
  }
  }', class = c("geojson", "json"))
  clip_poly <- geojson_sf(clip_poly)
  plot(clip_poly)

  out <- ms_clip(poly, clip_poly)
  plot(out, add = TRUE)
}