fm_evaluate: Methods for projecting to/from mesh objects

In fmesher: Triangle Meshes and Related Geometry Tools

Methods for projecting to/from mesh objects

Description

Calculate evaluation information and/or evaluate a function defined on a mesh or function space.

Usage

fm_evaluate(...)

## Default S3 method:
fm_evaluate(mesh, field, ...)

## S3 method for class 'fm_evaluator'
fm_evaluate(projector, field, ...)

## S3 method for class 'fm_basis'
fm_evaluate(basis, field, ...)

fm_evaluator(...)

## Default S3 method:
fm_evaluator(...)

## S3 method for class 'fm_mesh_3d'
fm_evaluator(mesh, loc = NULL, lattice = NULL, dims = NULL, ...)

## S3 method for class 'fm_mesh_2d'
fm_evaluator(mesh, loc = NULL, lattice = NULL, crs = NULL, ...)

## S3 method for class 'fm_mesh_1d'
fm_evaluator(mesh, loc = NULL, xlim = mesh$interval, dims = 100, ...)

fm_evaluator_lattice(mesh, ...)

## Default S3 method:
fm_evaluator_lattice(mesh, dims = 100, ...)

## S3 method for class 'fm_bbox'
fm_evaluator_lattice(mesh, dims = 100, ...)

## S3 method for class 'fm_mesh_2d'
fm_evaluator_lattice(
  mesh,
  xlim = NULL,
  ylim = NULL,
  dims = c(100, 100),
  projection = NULL,
  crs = NULL,
  ...
)

Arguments

...	Additional arguments passed on to methods.
mesh	An fm_mesh_1d, fm_mesh_2d, or other object supported by a sub-method.
field	Basis function weights, one per mesh basis function, describing the function to be evaluated at the projection locations
projector	An fm_evaluator object.
basis	An fm_basis object.
loc	Projection locations. Can be a matrix, SpatialPoints, SpatialPointsDataFrame, sf, sfc, or sfg object.
lattice	An fm_lattice_2d() object.
dims	Lattice dimensions.
crs	An optional CRS or inla.CRS object associated with loc and/or lattice.
xlim	X-axis limits for a lattice. For R2 meshes, defaults to covering the domain.
ylim	Y-axis limits for a lattice. For R2 meshes, defaults to covering the domain.
projection	One of c("default", "longlat", "longsinlat", "mollweide").

Value

A vector or matrix of the evaluated function

An fm_evaluator object

Methods (by class)

• fm_evaluate(default): The default method calls proj = fm_evaluator(mesh, ...), followed by fm_evaluate(proj, field).

Functions

• fm_evaluate(): Returns the field function evaluated at the locations determined by an fm_evaluator object. fm_evaluate(mesh, field = field, ...) is a shortcut to fm_evaluate(fm_evaluator(mesh, ...), field = field).

• fm_evaluator(): Returns an fm_evaluator list object with evaluation information. The proj element is a fm_basis object, containing (at least) a mapping matrix A and a logical vector ok, that indicates which locations were mappable to the input mesh. For fm_mesh_2d input, proj also contains a bary fm_bary object, with the barycentric coordinates within the triangle each input location falls in.

• fm_evaluator(default): The default method calls fm_basis and creates a basic fm_evaluator object

• fm_evaluator(fm_mesh_3d): The ... arguments are passed on to fm_evaluator_lattice() if no loc or lattice is provided.

• fm_evaluator(fm_mesh_2d): The ... arguments are passed on to fm_evaluator_lattice() if no loc or lattice is provided.

• fm_evaluator_lattice(): Create a lattice object by default covering the input mesh.

• fm_evaluator_lattice(default): Creates an fm_lattice_2d() object, by default covering the input mesh.

• fm_evaluator_lattice(fm_bbox): Creates an fm_lattice_Nd() object, by default covering the input mesh.

• fm_evaluator_lattice(fm_mesh_2d): Creates an fm_lattice_2d() object, by default covering the input mesh.

Author(s)

Finn Lindgren [e-mail]

See Also

fm_mesh_2d(), fm_mesh_1d(), fm_lattice_2d()

Examples

if (TRUE) {
  n <- 20
  loc <- matrix(runif(n * 2), n, 2)
  mesh <- fm_rcdt_2d_inla(loc, refine = list(max.edge = 0.05))
  proj <- fm_evaluator(mesh)
  field <- cos(mesh$loc[, 1] * 2 * pi * 3) * sin(mesh$loc[, 2] * 2 * pi * 7)
  image(proj$x, proj$y, fm_evaluate(proj, field))
}

# if (require("ggplot2") &&
#  require("ggpolypath")) {
#  ggplot() +
#    gg(data = fm_as_sfc(mesh), col = field)
# }

fmesher documentation built on April 3, 2025, 7:45 p.m.