sphereplot: Plot a spherical function or point set

In obreschkow/cooltools: Practical Tools for Scientific Computations and Visualizations

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 = NULL,
  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.

Author(s)

Danail Obreschkow

Examples

## 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 real spherical harmonics up to third degree
oldpar = par(mar=c(0,0,0,0))
nplot(xlim=c(-4,3.5),ylim=c(0,4),asp=1)
for (l in seq(0,3)) { # degree of spherical harmonic
  for (m in seq(-l,l)) { # order of spherical harmonic

    # make spherical harmonic function in real-valued convention
    f = function(theta,phi) sphericalharmonics(l,m,cbind(theta,phi))

    # plot spherical harmonic
    sphereplot(f, 50, col=planckcolors(100), phi0=0.1, theta0=pi/3, add=TRUE, clim=c(-0.7,0.7),
               center=c(m,3.5-l), radius=0.47)

    if (l==3) text(m,-0.15,sprintf('m=%+d',m))
  }
  text(-l-0.55,3.5-l,sprintf('l=%d',l),pos=2)
}
par(oldpar)

obreschkow/cooltools documentation built on Nov. 16, 2024, 2:46 a.m.