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ggplot2 geomes for fmesher related objects

Source: R/ggplot.R
geom_fm.Rd

[Experimental]

geom_fm is a generic function for generating geomes from various kinds of fmesher objects, e.g. fm_segm and fm_mesh_2d. The function invokes particular methods which depend on the class of the data argument. Requires the ggplot2 package.

Note: geom_fm is not yet a "proper" ggplot2 geom method; the interface may therefore change in the future.

Usage

geom_fm(mapping = NULL, data = NULL, ...)

# S3 method for fm_mesh_2d
geom_fm(
  mapping = NULL,
  data = NULL,
  mapping_int = NULL,
  mapping_bnd = NULL,
  defs_int = NULL,
  defs_bnd = NULL,
  ...,
  crs = NULL
)

# S3 method for fm_segm
geom_fm(mapping = NULL, data = NULL, ..., crs = NULL)

# S3 method for fm_mesh_1d
geom_fm(
  mapping = NULL,
  data = NULL,
  ...,
  xlim = NULL,
  basis = TRUE,
  knots = TRUE,
  derivatives = FALSE,
  weights = NULL
)

Arguments

mapping

an object for which to generate a geom.

data

an object for which to generate a geom.

...

Arguments passed on to the geom method.

mapping_int

aes for interior constraint edges.

mapping_bnd

aes for boundary edges.

defs_int

additional settings for interior constraint edges.

defs_bnd

additional settings for boundary edges.

crs

Optional crs to transform the object to before plotting.

xlim

numeric 2-vector; specifies the interval for which to compute functions. Default is data$interval

basis

logical; if TRUE (default), show the spline basis functions

knots

logical; if TRUE (default), show the spline knot locations

derivatives

logical; if TRUE (not default), draw first order derivatives instead of function values

weights

numeric vector; if provided, draw weighted basis functions and the resulting weighted sum.

Value

A combination of ggplot2 geoms.

Methods (by class)

  • geom_fm(fm_mesh_2d): Converts an fm_mesh_2d() object to sf with fm_as_sfc() and uses geom_sf to visualize the triangles and edges.

  • geom_fm(fm_segm): Converts an fm_segm() object to sf with fm_as_sfc() and uses geom_sf to visualize it.

  • geom_fm(fm_mesh_1d): Evaluates and plots the basis functions defined by an fm_mesh_1d() object.

Examples

ggplot() +
  geom_fm(data = fmexample$mesh)

m <- fm_mesh_2d(
  cbind(10, 20),
  boundary = fm_extensions(cbind(10, 20), c(25, 65)),
  max.edge = c(4, 10),
  crs = fm_crs("+proj=longlat")
)
ggplot() +
  geom_fm(data = m)

ggplot() +
  geom_fm(data = m, crs = fm_crs("epsg:27700"))

# \donttest{
# Compute a mesh vertex based function on a different grid
px <- fm_pixels(fm_transform(m, fm_crs("mollweide_globe")))
px$fun <- fm_evaluate(m,
  loc = px,
  field = sin(m$loc[, 1] / 5) * sin(m$loc[, 2] / 5)
)
ggplot() +
  geom_tile(aes(geometry = geometry, fill = fun),
    data = px,
    stat = "sf_coordinates"
  ) +
  geom_fm(
    data = m, alpha = 0.2, linewidth = 0.05,
    crs = fm_crs("mollweide_globe")
  )

# }
m <- fm_mesh_1d(c(1, 2, 4, 6, 10), boundary = c("n", "d"), degree = 2)
ggplot() +
  geom_fm(data = m, weights = c(4, 2, 4, -1))

m <- fm_mesh_1d(
  c(1, 2, 3, 5, 7),
  boundary = c("dirichlet", "neumann"),
  degree = 2
)
ggplot() +
  geom_fm(data = m)