graphx (version 1.0)

sphereplot: Plot a spherical function or point set

Description

Plots a spherical function or a point set in a 2D projection using only standard R graphics. This avoids compatibility issues of rgl, e.g. knitting markdown documents.

Usage

sphereplot(
  f,
  n = 100,
  theta0 = pi/2,
  phi0 = 0,
  angle = 0,
  projection = "globe",
  col = gray.colors(256, 0, 1),
  clim = NULL,
  add = FALSE,
  center = c(0, 0),
  radius = 1,
  nv = 500,
  show.border = TRUE,
  show.grid = TRUE,
  grid.phi = seq(0, 330, 30)/180 * pi,
  grid.theta = seq(30, 150, 30)/180 * pi,
  pch = 16,
  pt.col = "black",
  pt.cex = 0.5,
  lwd = 0.5,
  lty = 1,
  line.col = "black",
  background = "white",
  ...
)

Arguments

f

must be either of:

(1) NULL to plot just grid without spherical function

(2) a vectorized real function f(theta,phi) of the polar angle theta [0,pi] and azimuth angle [0,2pi]

(3) an n-by-2 array of values theta and phi

n

number of grid cells in each dimension used in the plot

theta0

polar angle in radians at the center of the projection

phi0

azimuth angle in radians at the center of the projection

angle

angle in radians between vertical axis and central longitudinal great circle

projection

type of projection: "globe" (default), "cylindrical", "mollweide"

col

color map

clim

2-element vector specifying the values of f corresponding to the first and last color in col

add

logical flag specifying whether the sphere is to be added to an existing plot

center

center of the sphere on the plot

radius

radius of the sphere on the plot

nv

number or vertices used for grid lines and border

show.border

logical flag specifying whether to show a circular border around the sphere

show.grid

logical flag specifying whether to show grid lines

grid.phi

vector of phi-values of the longitudinal grid lines

grid.theta

vector of theta-values of the latitudinal grid lines

pch

point type

pt.col

point color

pt.cex

point size

lwd

line width of grid lines and border

lty

line type of grid lines and border

line.col

color of grid lines and border

background

background color

...

additional arguments to be passed to the function f

Value

Returns a list containing the vector col of colors and 2-vector clim of values corresponding to the first and last color.

Examples

# NOT RUN {
## Plot random points on the unit sphere in Mollweide projection
set.seed(1)
f = cbind(acos(runif(5000,-1,1)),runif(5000,0,2*pi))
sphereplot(f,theta0=pi/3,projection='mollweide',pt.col='red')

## Plot a spherical function with color bar
nplot(xlim=c(0,1.2), asp=1)
f = function(theta,phi) cos(10*theta+phi)
sp = sphereplot(f, 200, col=planckcolors(200), phi0=0.1, theta0=pi/3,
add=TRUE, center=c(0.5,0.5), radius=0.4, clim=c(-1,1))
colorbar(1,0.1,1.1,0.9,col=sp$col,clim=sp$clim)

# }