R: Plot Empirical Variogram

plot.variogram {geoR} | R Documentation

## Plot Empirical Variogram

### Description

Plots sample (empirical) variogram computed using the function `variog`.

### Usage

    ## S3 method for class 'variogram'
    plot(x, max.dist, vario.col = "all", scaled = FALSE,
                   var.lines = FALSE, envelope.obj = NULL,
                   pts.range.cex, bin.cloud = FALSE,  ...)

### Arguments

`x` | an object of the class `"variogram"`, typically an output of the function `variog`.
`max.dist` | maximum distance for the x-axis. The default is the maximum distance for which the sample variogram was computed.
`vario.col` | only used if `obj` has information on more than one empirical variogram. The default `"all"` indicates that variograms of all variables should be plotted. Alternativelly a numerical vector can be used to select variables.
`scaled` | If `TRUE` the variogram values are divided by the sample variance. This allows comparison of variograms of variables measured in different scales.
`var.lines` | If `TRUE` a horizontal line is drawn at the value of the variance of the data (if `scaled = F`) or at 1 (if `scaled = T`).
`envelope.obj` | adds a variogram envelope computed by the function `variog.model.env` or `variog.mc.env`.
`pts.range.cex` | optional. A two elements vector with maximum and minimum values for the caracter expansion factor `cex`. If provided the point sizes in binned variogram are proportional to the number of pairs of points used to compute each bin.
`bin.cloud` | logical. If `TRUE` and the sample variogram was computed with the option `bin.cloud = TRUE`, box-plots of values at each bin are plotted instead of the empirical variograms.
`...` | other arguments to be passed to the function `plot` or `matplot`

### Details

This function plots empirical variograms. Toghether with `lines.variogram` can be used to compare sample variograms of different variables and to compare variogram models against the empirical variogram.

It uses the function `matplot` when plotting variograms for more them one variable.

### Value

Produces a plot with the sample variogram on the current graphics device. No values are returned.

### Author(s)

Paulo Justiniano Ribeiro Jr. paulojus@leg.ufpr.br,
Peter J. Diggle p.diggle@lancaster.ac.uk

### References

Further information on the package geoR can be found at:
http://www.leg.ufpr.br/geoR.

### See Also

`variog` for variogram calculations, `lines.variogram` and `lines.variomodel` for adding lines to the current plot, `variog.model.env` and `variog.mc.env` for variogram envelops computation, `matplot` for multiple lines plot and `plot` for generic plot function.

### Examples

    op <- par(no.readonly = TRUE)
    sim <- grf(100, cov.pars=c(1, .2)) # simulates data
    vario <- variog(sim, max.dist=1)   # computes sample variogram
    par(mfrow=c(2,2))
    plot(vario)                     # the sample variogram
    plot(vario, scaled = TRUE)      # the scaled sample variogram
    plot(vario, max.dist = 1)       # limiting the maximum distance
    plot(vario, pts.range = c(1,3)) # points sizes proportional to number of pairs
    par(op)

[Package geoR version 1.7-5.2 Index]