smoothcontour: Draw smoothed contours

Description

Draw smoothed iso-countours for a density field. The contours are computed using the contourLines routine and smoothed using the smooth.spline function. Both open and closed contour lines are handled correctly.

Usage

smoothcontour(
  x = seq(0, 1, length.out = nrow(z)),
  y = seq(0, 1, length.out = ncol(z)),
  z,
  levels,
  smoothing = 0.5,
  min.radius = 1,
  lwd = 1,
  lty = 1,
  col = "black",
  ...
)

Value

None

Arguments

x, y: vectors containing the locations of grid lines at which the values of z are measured. These must be in ascending order. By default, equally spaced values from 0 to 1 are used.
z: matrix representing the density field on which the contours are plotted.
levels: vector of the iso-contour levels.
smoothing: value between 0 and 1 specifying the degree of smoothing.
min.radius: numerical value. If larger than 0, all contours with a mean radius (in pixels) below min.radius are removed.
lwd: vector of line widths (see par)
lty: vector of line types (see par)
col: vector of colors (see par)
...: additional parameters to be passed to the function lines.

Author

Danail Obreschkow

Examples

Run this code

set.seed(1)
f = function(x) cos(2*x[1]-x[2]-1)^2*exp(-x[1]^2-x[2]^2-x[1]*x[2])
x = seq(-3,3,length=100)
m = pracma::meshgrid(x)
z = array(Vectorize(function(x,y) f(c(x,y)))(m$Y,m$X)+rnorm(4e4,sd=0.1),dim(m$X))
image(x,x,z,col=terrain.colors(100))
contour(x,x,z,levels=c(0.2,0.5),add=TRUE)
smoothcontour(x,x,z,levels=c(0.2,0.5),lwd=3,smoothing=0.8,min.radius=2)