s.density: 2-D scatter plot with kernel density estimation

Description

This function represents a two dimensional scatter plot of points distribution. Densities' representation is based on the levelplot graphic in lattice (density's surface, filled with colors and/or contour lines).

Usage

s.density(dfxy, xax = 1, yax = 2, bandwidth = NULL, gridsize = c(450L, 450L), 
  nrpoints = 300, threshold = 0.1, col = NULL, contour = FALSE, region = !contour, 
  nclass = 8, facets = NULL, plot = TRUE, storeData = TRUE, add = FALSE, pos = -1, ...)

Arguments

dfxy

a data frame used to produce the plot

xax

an integer (or a vector) indicating which column(s) of dfxy is(are) plotted on the x-axis

yax

an integer (or a vector) indicating which column(s) of dfxy is(are) plotted on the y-axis

bandwidth

bandwidth for density calculations which is passed in parameters in the bkde2D function of the KernSmooth package

gridsize

grid dimension

nrpoints

number of points on the density image

threshold

a value between 0 and 1 to draw densities greater than this threshold. No density is visible whether it is equal to 1

col

a color or a colors vector to color densities

contour

a logical to draw contour lines

region

a logical to fill grid regions with col

nclass

number of class for density

facets

a factor splitting the rows of dfxy so that subsets of the data are represented on different sub-graphics

plot

a logical indicating if the graphics is displayed

storeData

a logical indicating if the data should be stored in the returned object. If FALSE, only the names of the data arguments are stored

add

a logical. If TRUE, the graphic is superposed to the graphics already plotted in the current device

pos

an integer indicating the position of the environment where the data are stored, relative to the environment where the function is called. Useful only if storeData is FALSE

...

additional graphical parameters (see adegpar and trellis.par.get)

Value

An object of class ADEg (subclass S2.density) or ADEgS (if add is TRUE and/or if facets or vectors for xax/yax are used). The result is displayed if plot is TRUE.

Details

Density calculation is made using the kde2d function of the KernSmooth package.

Examples

Run this code

xx2 <- c(rnorm(50000, 1, 1), rnorm(50000, -1, 1))
yy2 <- c(rnorm(50000, -1, 0.5), rnorm(50000, 1, 0.5))
s.density(cbind(xx2, yy2), paxes.draw = TRUE, gridsize = c(200, 200), region = TRUE, 
  contour = TRUE, plabels.cex = 0, threshold = 0.05, nclass = 3, 
  col = colorRampPalette(c("lightgrey", "black"))(100))