Create Cell Geometry

Creates cell geometry from vectors of X and Y positions.

create_cell_geometry(
  X_coords,
  Y_coords,
  prj,
  geom = NULL,
  buffer_dist = 0,
  regularize = FALSE,
  eps = 1e-10
)

Arguments

X_coords

numeric center positions of X axis indices

Y_coords

numeric center positions of Y axis indices

prj

character proj4 string for x and y

geom

sf data.frame with geometry that cell geometry should cover

buffer_dist

numeric a distance to buffer the cell geometry in units of geom projection

regularize

boolean if TRUE, grid spacing will be adjusted to be exactly equal. Only applies to 1-d coordinates.

eps

numeric sets tolerance for grid regularity.

Details

Intersection is performed with cell centers then geometry is constructed. A buffer may be required to fully cover geometry with cells.

Examples

dir <- tempdir()
ncf <- file.path(dir, "metdata.nc") 

try(zip::unzip(system.file("extdata/metdata.zip", package = "ncdfgeom"), exdir = dir))

if(file.exists(ncf)) {

nc <- RNetCDF::open.nc(ncf)
ncmeta::nc_vars(nc)
variable_name <- "precipitation_amount"
cv <- ncmeta::nc_coord_var(nc, variable_name)

x <- RNetCDF::var.get.nc(nc, cv$X, unpack = TRUE)
y <- RNetCDF::var.get.nc(nc, cv$Y, unpack = TRUE)

prj <- ncmeta::nc_gm_to_prj(ncmeta::nc_grid_mapping_atts(nc))

geom <- sf::read_sf(system.file("shape/nc.shp", package = "sf"))
geom <- sf::st_transform(geom, 5070)

cell_geometry <- create_cell_geometry(x, y, prj, geom, 0)

plot(sf::st_geometry(cell_geometry), lwd = 0.25)
plot(sf::st_transform(sf::st_geometry(geom), prj), add = TRUE)

}
#> Warning: No variables with a grid mapping found.
#>  Defaulting to WGS84 Lon/Lat