contour.pemt {spMC}

Display Contours with Multi-directional Transiograms

Description

The function draws the 2-D sections contour plots of a multi-directional transiogram computed without any ellipsoidal interpolation and superpose the contour lines of the theoretical transition probabilities.

Usage

## S3 method for class 'pemt'
contour(x, nlevels = 10, col = c("black", "blue"), main,
     mar, ask = TRUE, ...)

Arguments

x

an object of class pemt.

nlevels

the number of levels to pass to the function contour.

col

a vector of two colors to pass to the function contour. The former color refers to the multi-directional transiogram, while the latter is used to draw contour lines of the theoretical transition probabilities.

main

the main title (on top) whose font and size are fixed.

mar

a scalar or a numerical vector of the form c(bottom, left, top, right) which gives the number of margin lines to be specified on the four sides of image to plot. See par(mar=.).

ask

a logical value; if TRUE, the user is asked for input, before each plot. See par(ask=.).

...

other arguments to pass to the function contour.

Details

A multidimensional transiogram is a diagram which shows the transition probabilities for a single pair of categories. The probability is computed for any lag vector h through

\mbox{expm} (\Vert h \Vert R_h),

where entries of R_h are not ellipsoidally interpolated, but they are estimated for the direction specified by the vector h.

The exponential matrix is evaluated by the scaling and squaring algorithm.

Value

An image is produced on the current graphics device. No values are returned.

Author(s)

Luca Sartore [e-mail]

References

Carle, S. F., Fogg, G. E. (1997) Modelling Spatial Variability with One and Multidimensional Continuous-Lag Markov Chains. Mathematical Geology, 29(7), 891-918.

Higham, N. J. (2008) Functions of Matrices: Theory and Computation. Society for Industrial and Applied Mathematics.

Sartore, L. (2010) Geostatistical models for 3-D data. M.Phil. thesis, Ca' Foscari University of Venice.

See Also

image.pemt, contour, plot.transiogram

Examples

data(ACM)

# Compute a 2-D section of a 
# multi-directional transiogram
psEmpTr <- pemt(ACM$MAT3, ACM[, 1:3], 2,
                max.dist = c(200, 200, 20), 
                which.dire=c(1, 3), 
                mle = "avg")

# Contour plots of 2-D sections of 
# multi-directional transiograms
contour(psEmpTr, mar = .7)