spClipPoint: Spatial - Clip (intersect) point vector layer with polygon...

In FIESTA: Forest Inventory Estimation and Analysis

Spatial - Clip (intersect) point vector layer with polygon vector layer.

Description

Wrapper for sf::st_intersection, to clip (intersect) point vector layer with a polygon vector layer.

Usage

spClipPoint(
  xyplt,
  xyplt_dsn = NULL,
  uniqueid = "PLT_CN",
  clippolyv,
  clippolyv_dsn = NULL,
  clippolyv.filter = NULL,
  showext = FALSE,
  keepNA = FALSE,
  returnsp = TRUE,
  othertabnms = NULL,
  stopifnotin = TRUE,
  savedata = FALSE,
  exportsp = FALSE,
  spMakeSpatial_opts = NULL,
  savedata_opts = NULL
)

Arguments

xyplt	sf R object or String. Point data to clip. Can be a spatial points object, full pathname to a shapefile, or name of a layer within a database.
xyplt_dsn	String. Data source name (dsn; e.g., sqlite or shapefile pathname) of layer to clip. The dsn varies by driver. See gdal OGR vector formats (https://www.gdal.org/ogr_formats.html).
uniqueid	String.* Unique identifier of xyplt rows.
clippolyv	sf R object or String. Name of clipping polygon spatial polygon object, full path to shapefile, or name of a layer within a database.
clippolyv_dsn	String. Data source name (dsn; e.g., sqlite or shapefile pathname) of clipping polygon. The dsn varies by driver. See gdal OGR vector formats (https://www.gdal.org/ogr_formats.html).
clippolyv.filter	String. Filter to subset clippolyv spatial layer.
showext	Logical. If TRUE, layer extents are displayed in plot window.
keepNA	Logical. If TRUE, keep NA values after data intersection.
returnsp	Logical. If TRUE, returns sf object of points. If FALSE, returns data frame of points (i.e., drops sf geometry).
othertabnms	String vector. Name(s) of R objects, comma-delimited files, or database layers to subset. Must include quotes (e.g., othertabnms=c("tree", "cond")).
stopifnotin	Logical. If TRUE, stops if boundaries do not overlap. If FALSE, returns NULL.
savedata	Logical. If TRUE, save data to outfolder.
exportsp	Logical. If TRUE, the clipped spatial point data are exported.
spMakeSpatial_opts	List. See help(spMakeSpatial_options()) for a list of options. Use to convert X/Y values to simple feature (sf) coordinates.
savedata_opts	List. See help(savedata_options()) for a list of options for saving data. If out_layer = NULL, default = 'pntclip'.

Details

The sf::st_intersection function is used to clip points.

If the projection of clippolyv is not the same as the xyplt, the xyplt layer layer will be reprojected to the same projection as the clippoly before intersection.

Value

A list of the following objects:

clip_xyplt	sf object. The input xyplt, clipped to polygon boundary layer. The projection will be same as clippolyv projection.
xy.uniqueid	String. Unique identifier of clip_xy.
clip_polyv	SpatialPolygonsDataFrame. The polygon boundary layer used for clipping.
clip_tabs	Data frame(s). Other tables in intabs clipped to boundary.

If exportsp=TRUE, the sf object will be written to out_dsn (See note).

Note

On-the-fly projection conversion
The spTransform (sf) method is used for on-the-fly map projection conversion and datum transformation using PROJ.4 arguments. Datum transformation only occurs if the +datum tag is present in the both the from and to PROJ.4 strings. The +towgs84 tag is used when no datum transformation is needed. PROJ.4 transformations assume NAD83 and WGS84 are identical unless other transformation parameters are specified. Be aware, providing inaccurate or incomplete CRS information may lead to erroneous data shifts when reprojecting. See spTransform help documentation for more details.

ESRI Shapefile Driver
If exportsp=TRUE:
The st_write (sf) function is called. If out_fmt="shp", the ESRI Shapefile driver truncates variable names to 10 characters or less. Variable names are changed before export using an internal function (trunc10shp). If sf object has more than 1 record, it will be returned but not exported.

Author(s)

Tracey S. Frescino

Examples

# Get point data from WYplt data in FIESTA
WYplt <- FIESTA::WYplt

# Get polygon vector layer from FIESTA external data
WYbhdistfn <- system.file("extdata",
                          "sp_data/WYbighorn_districtbnd.shp",
                          package = "FIESTA")

# Extract points from polygon vector layer
xyext <- spClipPoint(xyplt = WYplt,
                     clippolyv = WYbhdistfn,
                     clippolyv.filter = "DISTRICTNU == '03'",
                     uniqueid = "CN",
                     spMakeSpatial_opts = list(xvar = "LON_PUBLIC",
                                               yvar = "LAT_PUBLIC",
                                               xy.crs = 4269))
names(xyext)
xyplt <- xyext$clip_xyplt
polyv <- xyext$clip_polyv

# Plot extracted values of national forest district
plot(sf::st_geometry(polyv))
plot(sf::st_geometry(xyplt), add = TRUE)

FIESTA documentation built on Nov. 22, 2023, 1:07 a.m.