fMultivar (version 3042.80)

utils-density2d: Bivariate Density Tools

Description

Kernel density estimator and histogram counter for bivariate distributions

Usage

density2d(x, y = NULL, n = 20, h = NULL, limits = c(range(x), range(y))) 
hist2d(x, y = NULL, n = c(20, 20))

Arguments

x, y

two vectors of coordinates of data. If y is NULL then x is assumed to be a two column matrix, where the first column contains the x data, and the second column the y data.

n

n - an integer specifying the number of grid points in each direction. The default value is 20. [hist2D] - In this case n may be a scalar or a two element vector. The default value is 20.

h

a vector of bandwidths for x and y directions. Defaults to normal reference bandwidth.

limits

the limits of the rectangle covered by the grid.

Value

density2d and hist2d return a list with three elements $x, $y, and $z. x and y are vectors spanning the two dimensional grid and z the corresponding matrix. The output can directly serve as input to the plotting functions image, contour and persp.

References

Azzalini A., (2004); The sn Package; R Reference Guide available from www.r-project.org.

Venables W.N., Ripley B.D., (2002); Modern Applied Statistics with S, Fourth Edition, Springer.

Warnes G.R., (2004); The gregmisc Package; R Reference Guide available from www.r-project.org.

Examples

# NOT RUN {
## hist2d - 
   # Normal Random Numbers:
   set.seed(4711)
   X <- rnorm2d(40000)
   # 2D Histogram Plot:
   Z <- hist2d(X)
   image(Z)
   contour(Z, add=TRUE)
# }