parameter c in [0,1]. c = 0 corresponds to complete inhibition at distances up to r.
r
inhibition distance
Details
Uses spatial birth-and-death process for 4n steps, or for 40n steps
starting from a binomial pattern on the first call from an other function.
Uses the region set by ppinit or ppregion.
Value
list of vectors of x and y coordinates
Side Effects
uses the random number generator
References
Ripley, B. D. (1981) Spatial Statistics. Wiley.
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
Compute analysis of variance tables for one or more
fitted trend surface model objects; where anova.trls is
called with multiple objects, it passes on the arguments to
anovalist.trls.
Usage
## S3 method for class 'trls'
anova(object,...)
anovalist.trls(object,...)
Arguments
object
A fitted trend surface model object from surf.ls
...
Further objects of the same kind
Value
anova.trls and anovalist.trls return objects corresponding
to their printed tabular output.
References
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
Compute spatial correlograms of spatial data or residuals.
Usage
correlogram(krig, nint, plotit =TRUE,...)
Arguments
krig
trend-surface or kriging object with columns x, y, and z
nint
number of bins used
plotit
logical for plotting
...
parameters for the plot
Details
Divides range of data into nint bins, and computes the covariance for
pairs with separation in each bin, then divides by the variance.
Returns results for bins with 6 or more pairs.
Value
x and y coordinates of the correlogram, and cnt, the number of pairs
averaged per bin.
Side Effects
Plots the correlogram if plotit = TRUE.
References
Ripley, B. D. (1981) Spatial Statistics. Wiley.
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
Predicted values based on trend surface model object
Usage
## S3 method for class 'trls'
predict(object, x, y,...)
Arguments
object
Fitted trend surface model object returned by surf.ls
x
Vector of prediction location eastings (x coordinates)
y
Vector of prediction location northings (y coordinates)
...
further arguments passed to or from other methods.
Value
predict.trls produces a vector of predictions corresponding
to the prediction locations. To display the output with image
or contour, use trmat or convert the returned vector
to matrix form.
References
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
Evaluate Kriging standard error of prediction over a grid.
Usage
semat(obj, xl, xu, yl, yu, n, se)
Arguments
obj
object returned by surf.gls
xl
limits of the rectangle for grid
xu
ditto
yl
ditto
yu
ditto
n
use n x n grid within the rectangle
se
standard error at distance zero as a multiple of the supplied
covariance. Otherwise estimated, and it assumed that a correlation
function was supplied.
Value
list with components x, y and z suitable for contour and image.
References
Ripley, B. D. (1981) Spatial Statistics. Wiley.
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
This function provides the basic quantities which are used in
forming a variety of diagnostics for checking the quality of
regression fits for trend surfaces calculated by surf.ls.
Usage
trls.influence(object)## S3 method for class 'trls'
plot(x, border ="red", col =NA, pch =4, cex =0.6,
add =FALSE, div =8,...)
Arguments
object, x
Fitted trend surface model from surf.ls
div
scaling factor for influence circle radii in plot.trls
add
add influence plot to existing graphics if TRUE
border, col, pch, cex, ...
additional graphical parameters
Value
trls.influence returns a list with components:
r
raw residuals as given by residuals.trls
hii
diagonal elements of the Hat matrix
stresid
standardised residuals
Di
Cook's statistic
References
Unwin, D. J., Wrigley, N. (1987) Towards a general-theory of
control point distribution effects in trend surface models.
Computers and Geosciences,13, 351–355.
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.
Compute spatial (semi-)variogram of spatial data or residuals.
Usage
variogram(krig, nint, plotit =TRUE,...)
Arguments
krig
trend-surface or kriging object with columns x, y, and z
nint
number of bins used
plotit
logical for plotting
...
parameters for the plot
Details
Divides range of data into nint bins, and computes the average squared
difference for pairs with separation in each bin. Returns results for
bins with 6 or more pairs.
Value
x and y coordinates of the variogram and cnt,
the number of pairs averaged per bin.
Side Effects
Plots the variogram if plotit = TRUE
References
Ripley, B. D. (1981) Spatial Statistics. Wiley.
Venables, W. N. and Ripley, B. D. (2002)
Modern Applied Statistics with S. Fourth edition. Springer.