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#' @include deprecated.R
#' @title Generate lattice points covering a mesh
#'
#' @description Generate `terra`, `sf`, or `sp` lattice locations
#'
#' @export
#'
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#'
#' @param mesh An `fm_mesh_2d` object
#' @param dims A length 2 integer vector giving the dimensions of
#' the target lattice.
#' @param xlim,ylim Length 2 numeric vectors of x- and y- axis limits.
#' Defaults taken from the range of the mesh or mask; see `minimal`.
#' @param 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.
#' @param format character; "sf", "terra" or "sp"
#' @param 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.
#' @param nx `r lifecycle::badge("deprecated")` Number of pixels in x direction,
#' or a numeric vector of x-values
#' @param ny `r lifecycle::badge("deprecated")` Number of pixels in y direction,
#' or a numeric vector of y-values
#' @return `sf`, `SpatRaster`, or `SpatialPixelsDataFrame` covering the mesh or
#' mask.
#'
#' @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$mesh), alpha = 0.2)
#' }
#'
#' \donttest{
#' if (require("ggplot2", quietly = TRUE) &&
#' require("terra", quietly = TRUE) &&
#' require("tidyterra", quietly = TRUE)) {
#' pxl <- fm_pixels(fmexample$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)
#' }
#' }
fm_pixels <- function(mesh,
dims = c(150, 150),
xlim = NULL,
ylim = NULL,
mask = TRUE,
format = "sf",
minimal = TRUE,
nx = deprecated(),
ny = deprecated()) {
format <- match.arg(format, c("sf", "terra", "sp"))
if (!fm_manifold(mesh, "R2")) {
stop("fmesher::fm_pixels() currently works for R2 meshes only.")
}
if (is.null(mask)) {
mask <- FALSE
}
x <- NULL
if (lifecycle::is_present(nx)) {
lifecycle::deprecate_soft(
"0.0.1",
"fm_pixels(nx)",
"fm_pixels(dim)"
)
if (length(nx) == 1) {
dims[1] <- nx
} else {
x <- nx
}
}
y <- NULL
if (lifecycle::is_present(ny)) {
lifecycle::deprecate_soft(
"0.0.1",
"fm_pixels(ny)",
"fm_pixels(dim)"
)
if (length(ny) == 1) {
dims[2] <- ny
} else {
y <- ny
}
}
if (!is.logical(mask)) {
if (inherits(mask, "SpatialPolygonsDataFrame")) {
mask <- as(mask, "SpatialPolygons")
}
mask <- sf::st_as_sf(mask)
mask_bbox <- sf::st_bbox(mask)
}
if (is.null(x)) {
if (is.null(xlim)) {
xlim <- range(mesh$loc[, 1])
if (!is.logical(mask) && minimal) {
xlim <- c(max(xlim[1], mask_bbox[1]), min(xlim[2], mask_bbox[3]))
}
}
x <- seq(xlim[1], xlim[2], length.out = dims[1])
}
if (is.null(y)) {
if (is.null(ylim)) {
ylim <- range(mesh$loc[, 2])
if (!is.logical(mask) && minimal) {
ylim <- c(max(ylim[1], mask_bbox[2]), min(ylim[2], mask_bbox[4]))
}
}
y <- seq(ylim[1], ylim[2], length.out = dims[2])
}
pixels <- expand.grid(x = x, y = y)
pixels <- sf::st_as_sf(pixels, coords = c("x", "y"), crs = fm_crs(mesh))
pixels_within <- rep(TRUE, NROW(pixels))
if (is.null(mask)) {
mask <- FALSE
}
if (is.logical(mask)) {
if (mask) {
pixels_within <- fm_is_within(pixels, mesh)
pixels <- pixels[pixels_within, , drop = FALSE]
}
} else {
if (inherits(mask, "SpatialPolygonsDataFrame")) {
mask <- as(mask, "SpatialPolygons")
}
mask <- sf::st_as_sf(mask)
pixels_within <- sf::st_within(pixels, mask)
pixels_within <- lengths(pixels_within) > 0
pixels <- pixels[pixels_within, , drop = FALSE]
}
if (identical(format, "sp")) {
pixels <- as(pixels, "Spatial")
pixels <- as(pixels, "SpatialPixelsDataFrame")
} else if (identical(format, "terra")) {
fm_require_stop("terra")
pixels <- as(pixels, "Spatial")
pixels <- as(pixels, "SpatialPixelsDataFrame")
pixels$.mask <- TRUE
pixels <- terra::rast(pixels)
}
pixels
}
#' @title Refine a 2d mesh
#'
#' @description Refine an existing mesh
#'
#' @keywords internal
#'
#' @param mesh An [fm_mesh_2d()] object
#' @param refine A list of refinement options passed on to
#' [fm_rcdt_2d_inla]
#' @return A refined `fm_mesh_2d` object
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#' @export
#' @examples
#' fm_dof(fmexample$mesh)
#' fm_dof(fm_refine(fmexample$mesh, refine = list(max.edge = 1)))
#'
fm_refine <- function(mesh, refine = list(max.edge = 1)) {
rmesh <- fm_rcdt_2d_inla(
loc = mesh$loc,
boundary = fm_segm(mesh, boundary = TRUE),
interior = fm_segm(mesh, boundary = FALSE),
crs = fm_crs(mesh),
refine = refine
)
return(rmesh)
}
#' Split triangles of a mesh into subtriangles
#'
#' `r lifecycle::badge("experimental")`
#' Splits each mesh triangle into `(n + 1)^2` subtriangles.
#' The current version drops any edge constraint information from the mesh.
#'
#' @param mesh an [fm_mesh_2d] object
#' @param n number of added points along each edge. Default is 1.
#' @return A refined [fm_mesh_2d] object
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#' @export
#' @examples
#' mesh <- fm_rcdt_2d_inla(
#' loc = rbind(c(0, 0), c(1, 0), c(0, 1)),
#' tv = rbind(c(1, 2, 3))
#' )
#' mesh_sub <- fm_subdivide(mesh, 3)
#' mesh
#' mesh_sub
#'
#' plot(mesh_sub, edge.color = 2)
#'
#' plot(fm_subdivide(fmexample$mesh, 3), edge.color = 2)
#' plot(fmexample$mesh, add = TRUE, edge.color = 1)
fm_subdivide <- function(mesh, n = 1) {
if (n < 1) {
return(mesh)
}
sub <- fmesher_subdivide(
mesh_loc = mesh$loc,
mesh_tv = mesh$graph$tv - 1L,
mesh_boundary = mesh$segm$bnd$idx - 1L,
mesh_interior = mesh$segm$int$idx - 1L,
subdivisions = n,
options = list()
)
if (fm_manifold(mesh, "S2")) {
radius <- mean(rowSums(mesh$loc^2)^0.5)
renorm <- function(loc) {
loc * (radius / rowSums(loc^2)^0.5)
}
sub$loc <- renorm(sub$loc)
}
new_mesh <- fm_rcdt_2d_inla(
loc = sub$loc,
tv = sub$tv + 1L,
crs = fm_crs(mesh)
)
new_mesh
}
join_segm <- function(...) {
segm_list <- list(...)
loc <- matrix(0, 0, 3)
idx <- matrix(0, 0, 2)
for (k in seq_along(segm_list)) {
idx <- rbind(idx, segm_list[[k]]$idx + nrow(loc))
loc <- rbind(loc, segm_list[[k]]$loc)
}
# Collapse duplicate points
new_loc <- loc
new_idx <- seq_len(nrow(loc))
prev_idx <- 0
for (k in seq_len(nrow(loc))) {
if (any(is.na(new_loc[k, ]))) {
new_idx[k] <- NA
} else {
if (prev_idx == 0) {
prev_dist <- 1
} else {
prev_dist <- ((new_loc[seq_len(prev_idx), 1] - new_loc[k, 1])^2 +
(new_loc[seq_len(prev_idx), 2] - new_loc[k, 2])^2 +
(new_loc[seq_len(prev_idx), 3] - new_loc[k, 3])^2)^0.5
}
if (all(prev_dist > 0)) {
prev_idx <- prev_idx + 1
new_idx[k] <- prev_idx
new_loc[prev_idx, ] <- new_loc[k, ]
} else {
new_idx[k] <- which.min(prev_dist)
}
}
}
idx <- matrix(new_idx[idx], nrow(idx), 2)
# Remove NA and atomic lines
ok <-
!is.na(idx[, 1]) &
!is.na(idx[, 2]) &
idx[, 1] != idx[, 2]
idx <- idx[ok, , drop = FALSE]
# Set locations
loc <- new_loc[seq_len(prev_idx), , drop = FALSE]
fm_segm(
loc = loc,
idx = idx,
is.bnd = FALSE
)
}
#' Construct the intersection mesh of a mesh and a polygon
#'
#' @param mesh `fm_mesh_2d` object to be intersected
#' @param poly `fm_segm` object with a closed polygon
#' to intersect with the mesh
#' @returns An [fm_mesh_2d] object
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#' @keywords internal
#' @export
#' @examples
#' segm <- fm_segm(rbind(c(-4, -4), c(4, -4), c(0, 4)),
#' is.bnd = TRUE
#' )
#' str(m <- fm_mesh_intersection(fmexample$mesh, segm))
#' plot(fmexample$mesh)
#' lines(segm, col = 4)
#' plot(m, edge.color = 2, add = TRUE)
fm_mesh_intersection <- function(mesh, poly) {
if (ncol(poly$loc) < 3) {
poly$loc <- cbind(poly$loc, 0)
}
all_edges <- fm_segm(
loc = mesh$loc,
idx = cbind(
as.vector(t(mesh$graph$tv)),
as.vector(t(mesh$graph$tv[, c(2, 3, 1), drop = FALSE]))
),
is.bnd = FALSE
)
mesh_cover <- fm_rcdt_2d_inla(
loc = rbind(mesh$loc, poly$loc),
interior = all_edges
)
split_segm <- fm_split_lines(mesh_cover, segm = poly)
joint_segm <- join_segm(split_segm, all_edges)
mesh_joint_cover <- fm_rcdt_2d_inla(
interior = joint_segm,
extend = TRUE
)
mesh_poly <- fm_rcdt_2d_inla(boundary = poly)
loc_tri <-
(mesh_joint_cover$loc[mesh_joint_cover$graph$tv[, 1], , drop = FALSE] +
mesh_joint_cover$loc[mesh_joint_cover$graph$tv[, 2], , drop = FALSE] +
mesh_joint_cover$loc[mesh_joint_cover$graph$tv[, 3], , drop = FALSE]) / 3
ok_tri <-
fm_is_within(loc_tri, mesh) &
fm_is_within(loc_tri, mesh_poly)
if (any(ok_tri)) {
loc_subset <- unique(sort(as.vector(mesh_joint_cover$graph$tv[ok_tri, , drop = FALSE])))
new_idx <- integer(mesh$n)
new_idx[loc_subset] <- seq_along(loc_subset)
tv_subset <- matrix(new_idx[mesh_joint_cover$graph$tv[ok_tri, , drop = FALSE]],
ncol = 3
)
loc_subset <- mesh_joint_cover$loc[loc_subset, , drop = FALSE]
mesh_subset <- fm_rcdt_2d_inla(
loc = loc_subset,
tv = tv_subset,
extend = FALSE
)
} else {
mesh_subset <- NULL
}
mesh_subset
}
#' @title Store points in different formats
#'
#' @description Convert a matrix of points into different formats.
#'
#' @param loc a coordinate matrix
#' @param crs CRS information to associate with the coordinates
#' @param info An optional data.frame of additional data
#' @param format character; `"sf"`, `"df"`, `"sp"`
#' @return
#' An `sf`, `data.frame`, or `SpatialPointsDataFrame` object, with
#' optional added information.
#' @export
#' @keywords internal
#' @examples
#' fm_store_points(fmexample$loc, format = "sf")
#'
fm_store_points <- function(loc, crs = NULL, info = NULL, format = NULL) {
format <- match.arg(
format,
c("sf", "df", "sp")
)
crs <- fm_crs(crs)
points <- as.data.frame(loc)
colnames(points) <- c("x", "y", "z")[seq_len(ncol(points))]
if (!fm_crs_is_null(crs) && !fm_crs_is_geocent(crs)) {
points <- points[, 1:2, drop = FALSE]
}
if (identical(format, "df")) {
if (!is.null(info)) {
points <- cbind(points, info)
}
} else if (identical(format, "sp")) {
points <- sp::SpatialPointsDataFrame(
points,
data = info,
proj4string = fm_CRS(crs)
)
} else if (identical(format, "sf")) {
if (is.null(info)) {
points <- sf::st_as_sf(
points,
coords = seq_len(ncol(points)),
crs = crs
)
} else {
points <- sf::st_as_sf(
cbind(points, info),
coords = seq_len(ncol(points)),
crs = crs
)
}
}
points # return
}
#' @title Extract vertex locations from an `fm_mesh_2d`
#'
#' @description Extracts the vertices of an `fm_mesh_2d` object.
#'
#' @export
#' @param x An `fm_mesh_2d` object.
#' @param format character; `"sf"`, `"df"`, `"sp"`
#' @return
#' An `sf`, `data.frame`, or `SpatialPointsDataFrame` object, with the vertex
#' coordinates, and a `.vertex` column with the vertex indices.
#'
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#' @seealso [fm_centroids()]
#'
#' @examples
#' if (require("ggplot2", quietly = TRUE)) {
#' vrt <- fm_vertices(fmexample$mesh, format = "sf")
#' ggplot() +
#' geom_sf(data = fm_as_sfc(fmexample$mesh)) +
#' geom_sf(data = vrt, color = "red")
#' }
#'
fm_vertices <- function(x, format = NULL) {
fm_store_points(
loc = x$loc,
info = data.frame(.vertex = seq_len(nrow(x$loc))),
crs = fm_crs(x),
format = format
)
}
#' @title Extract triangle centroids from an `fm_mesh_2d`
#'
#' @description Computes the centroids of the triangles of an [fm_mesh_2d()]
#' object.
#'
#' @export
#' @param x An `fm_mesh_2d` or `inla.mesh` object.
#' @param format character; `"sf"`, `"df"`, `"sp"`
#' @return
#' An `sf`, `data.frame`, or `SpatialPointsDataFrame` object, with the vertex
#' coordinates, and a `.triangle` column with the triangle indices.
#'
#' @author Finn Lindgren \email{finn.lindgren@@gmail.com}
#' @seealso [fm_vertices()]
#'
#' @examples
#' if (require("ggplot2", quietly = TRUE)) {
#' vrt <- fm_centroids(fmexample$mesh, format = "sf")
#' ggplot() +
#' geom_sf(data = fm_as_sfc(fmexample$mesh)) +
#' geom_sf(data = vrt, color = "red")
#' }
#'
fm_centroids <- function(x, format = NULL) {
## Extract triangle centroids
loc <- (x$loc[x$graph$tv[, 1], , drop = FALSE] +
x$loc[x$graph$tv[, 2], , drop = FALSE] +
x$loc[x$graph$tv[, 3], , drop = FALSE]) / 3
if (fm_manifold(x, "S2")) {
loc <- loc / rowSums(loc^2)^0.5 * sum(x$loc[1, ]^2)^0.5
}
fm_store_points(
loc = loc,
info = data.frame(.triangle = seq_len(nrow(loc))),
crs = fm_crs(x),
format = format
)
}
# Convert loc information to raw matrix coordinates for the mesh
fm_onto_mesh <- function(mesh, loc, crs = NULL) {
if (!is.matrix(loc) && !fm_crs_is_null(crs)) {
warning("loc is non-matrix but crs specified; will be ignored")
}
if (inherits(loc, c(
"SpatialPoints", "SpatialPointsDataFrame",
"sf", "sfc", "sfg"
))) {
crs <- fm_crs(loc)
}
mesh_crs <- fm_crs(mesh)
loc_needs_normalisation <- FALSE
if (!fm_crs_is_null(crs) && !fm_crs_is_null(mesh_crs)) {
if (fm_crs_is_geocent(mesh_crs)) {
if (!is.matrix(loc)) {
if (!fm_crs_is_identical(crs, mesh_crs)) {
loc <- fm_transform(loc, crs = mesh_crs, crs0 = crs)
}
}
} else if (!fm_crs_is_identical(crs, mesh_crs)) {
loc <- fm_transform(loc, crs = mesh_crs, crs0 = crs, passthrough = TRUE)
}
} else if (fm_manifold(mesh, "S2")) {
loc_needs_normalisation <- TRUE
}
if (inherits(loc, c("SpatialPoints", "SpatialPointsDataFrame"))) {
loc <- sp::coordinates(loc)
} else if (inherits(loc, c("sf", "sfc", "sfg"))) {
loc <- sf::st_coordinates(loc)
c_names <- colnames(loc)
c_names <- intersect(c_names, c("X", "Y", "Z"))
loc <- loc[, c_names, drop = FALSE]
} else if (!is.matrix(loc)) {
warning(
paste0(
"Unclear if the 'loc' class ('",
paste0(class(loc), collapse = "', '"),
"') is of a type we know how to handle."
),
immediate. = TRUE
)
}
if (loc_needs_normalisation) {
loc <- loc / rowSums(loc^2)^0.5 * mean(rowSums(mesh$loc^2)^0.5)
}
loc
}
#' @title Function spece degrees of freedom
#'
#' @description
#' Obtain the degrees of freedom of a function space, i.e.
#' the number of basis functions it uses.
#'
#' @param x A function space object, such as [fm_mesh_1d()] or
#' [fm_mesh_2d()]
#' @returns An integer
#' @export
#' @examples
#' fm_dof(fmexample$mesh)
#'
fm_dof <- function(x) {
UseMethod("fm_dof")
}
#' @rdname fm_dof
#' @export
fm_dof.fm_mesh_1d <- function(x) {
as.integer(x[["m"]])
}
#' @rdname fm_dof
#' @export
fm_dof.fm_mesh_2d <- function(x) {
as.integer(x[["n"]])
}
#' @rdname fm_dof
#' @export
fm_dof.fm_tensor <- function(x) {
prod(vapply(x$fun_spaces, fm_dof, 0L))
}
# Deprecated ####
#' @describeIn fmesher-deprecated Conversion to inla.mesh.segment
#' `r lifecycle::badge("deprecated")` in favour of [fm_as_segm()].
#' @returns An `fm_segm` object
#' @export
fm_as_inla_mesh_segment <-
function(...) {
lifecycle::deprecate_soft(
"0.0.1",
"fm_as_inla_mesh_segment()",
"fm_as_segm()"
)
fm_as_segm(...)
}
#' @describeIn fmesher-deprecated Conversion to inla.mesh.
#' `r lifecycle::badge("deprecated")` in favour of [fm_as_mesh_2d()].
#' @returns An `fm_mesh_2d` object
#' @export
fm_as_inla_mesh <- function(...) {
lifecycle::deprecate_soft(
"0.0.1",
"fm_as_inla_mesh()",
"fm_as_mesh_2d()"
)
fm_as_mesh_2d(...)
}
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