fm_pixels {fmesher}

Generate lattice points covering a mesh

Description

Generate terra, sf, or sp lattice locations

Usage

fm_pixels(
  mesh,
  dims = c(150, 150),
  xlim = NULL,
  ylim = NULL,
  mask = TRUE,
  format = "sf",
  minimal = TRUE,
  nx = deprecated(),
  ny = deprecated()
)

Arguments

mesh

An fm_mesh_2d object

dims

A length 2 integer vector giving the dimensions of the target lattice.

xlim, ylim

Length 2 numeric vectors of x- and y- axis limits. Defaults taken from the range of the mesh or mask; see minimal.

mask

If logical and TRUE, remove pixels that are outside the mesh. If mask is an sf or Spatial object, only return pixels covered by this object.

format

character; "sf", "terra" or "sp"

minimal

logical; if TRUE (default), the default range is determined by the minimum of the ranges of the mesh and mask, otherwise only the mesh.

nx

Number of pixels in x direction, or a numeric vector of x-values

ny

Number of pixels in y direction, or a numeric vector of y-values

Value

sf, SpatRaster, or SpatialPixelsDataFrame covering the mesh or mask.

Author(s)

Finn Lindgren [e-mail]

Examples

if (require("ggplot2", quietly = TRUE)) {
  dims <- c(50, 50)
  pxl <- fm_pixels(
    fmexample$mesh,
    dims = dims,
    mask = fmexample$boundary_sf[[1]],
    minimal = TRUE
  )
  pxl$val <- rnorm(NROW(pxl)) +
    fm_evaluate(fmexample$mesh, pxl, field = 2 * fmexample$mesh$loc[, 1])
  ggplot() +
    geom_tile(
      data = pxl,
      aes(geometry = geometry, fill = val),
      stat = "sf_coordinates"
    ) +
    geom_sf(data = fm_as_sfc(fmexample$mesh), alpha = 0.2)
}


if (require("ggplot2", quietly = TRUE) &&
  require("terra", quietly = TRUE) &&
  require("tidyterra", quietly = TRUE)) {
  pxl <- fm_pixels(fmexample$mesh,
    dims = c(50, 50), mask = fmexample$boundary_sf[[1]],
    format = "terra"
  )
  pxl$val <- rnorm(NROW(pxl) * NCOL(pxl))
  pxl <-
    terra::mask(
      pxl,
      mask = pxl$.mask,
      maskvalues = c(FALSE, NA),
      updatevalue = NA
    )
  ggplot() +
    geom_spatraster(data = pxl, aes(fill = val)) +
    geom_sf(data = fm_as_sfc(fmexample$mesh), alpha = 0.2)
}