fmesher (version 0.3.0)

fm_crs_plot: Plot CRS and fm_crs objects

Description

Plot the outline of a crs or fm_crs() projection, with optional graticules (transformed parallels and meridians) and Tissot indicatrices.

Usage

fm_crs_plot(
  x,
  xlim = NULL,
  ylim = NULL,
  outline = TRUE,
  graticule = c(15, 15, 45),
  tissot = c(30, 30, 30),
  asp = 1,
  add = FALSE,
  eps = 0.05,
  ...
)
fm_crs_graticule(
  x,
  by = c(15, 15, 45),
  add = FALSE,
  do.plot = TRUE,
  eps = 0.05,
  ...
)
fm_crs_tissot(
  x,
  by = c(30, 30, 30),
  add = FALSE,
  do.plot = TRUE,
  eps = 0.05,
  diff.eps = 0.01,
  ...
)

Value

NULL, invisibly

Arguments

x

A crs or fm_crs() object.

xlim

Optional x-axis limits.

ylim

Optional y-axis limits.

outline

Logical, if TRUE, draw the outline of the projection.

graticule

Vector of length at most 3, to plot meridians with spacing graticule[1] degrees and parallels with spacing graticule[2] degrees. graticule[3] optionally specifies the spacing above and below the first and last parallel. When graticule[1]==0 no meridians are drawn, and when graticule[2]==0 no parallels are drawn. Use graticule=NULL to skip drawing a graticule.

tissot

Vector of length at most 3, to plot Tissot's indicatrices with spacing tissot[1] degrees and parallels with spacing tissot[2] degrees. tissot[3] specifices a scaling factor. Use tissot=NULL to skip drawing a Tissot's indicatrices.

asp

The aspect ratio for the plot, default 1.

add

If TRUE, add the projecton plot to an existing plot.

eps

Clipping tolerance for rudimentary boundary clipping

...

Additional arguments passed on to the internal calls to plot and lines.

by

The spacing between (long, lat, long_at_poles) graticules/indicatrices, see the graticule and tissot arguments.

do.plot

logical; If TRUE, do plotting

diff.eps

Pre-scaling

Functions

• fm_crs_graticule(): Constructs graticule information for a given CRS or fm_crs() and optionally plots the graticules. Returns a list with two elements, meridians and parallels, which are SpatialLines objects.

• fm_crs_tissot(): Constructs Tissot indicatrix information for a given CRS or fm_crs() and optionally plots the indicatrices. Returns a list with one element, tissot, which is a SpatialLines object.

Author

Finn Lindgren

See Also

fm_crs()

Examples

# \donttest{
if (require("sf") && require("sp")) {
  for (projtype in c(
    "longlat_norm",
    "lambert_norm",
    "mollweide_norm",
    "hammer_norm"
  )) {
    fm_crs_plot(fm_crs(projtype), main = projtype)
  }
}

if (require("sf") && require("sp")) {
  oblique <- c(0, 45, 45, 0)
  for (projtype in c(
    "longlat_norm",
    "lambert_norm",
    "mollweide_norm",
    "hammer_norm"
  )) {
    fm_crs_plot(
      fm_crs(projtype, oblique = oblique),
      main = paste("oblique", projtype)
    )
  }
}
# }