plot.leverage.ppm | R Documentation |
Generate a pixel image plot, or a contour plot, or a perspective plot,
of a leverage function that has been computed by leverage.ppm
.
## S3 method for class 'leverage.ppm'
plot(x, ...,
what=c("smooth", "nearest", "exact"),
showcut=TRUE,
args.cut=list(drawlabels=FALSE),
multiplot=TRUE)
## S3 method for class 'leverage.ppm'
contour(x, ...,
what=c("smooth", "nearest"),
showcut=TRUE,
args.cut=list(col=3, lwd=3, drawlabels=FALSE),
multiplot=TRUE)
## S3 method for class 'leverage.ppm'
persp(x, ...,
what=c("smooth", "nearest"),
main, zlab="leverage")
x |
Leverage function (object of class |
... |
Arguments passed to |
what |
Character string (partially matched) specifying the values to be plotted. See Details. |
showcut |
Logical. If |
args.cut |
Optional list of arguments passed to
|
multiplot |
Logical value indicating whether it is permissible to display several plot panels. |
main |
Optional main title. A character string or character vector. |
zlab |
Label for the |
These functions are the plot
, contour
and persp
methods
for objects of class "leverage.ppm"
.
Such objects are computed by the command leverage.ppm
.
The plot
method displays the leverage function
as a colour pixel image using plot.im
,
and draws a single contour line at the mean leverage value
using contour.default
.
Use the argument clipwin
to restrict the plot to a subset
of the full data.
The contour
method displays the leverage function as a contour
plot, and also draws a single contour line at the mean leverage value,
using contour.im
.
The persp
method displays the leverage function as a surface
in perspective view, using persp.im
.
Since the exact values of leverage are computed only at a finite set of quadrature locations, there are several options for these plots:
what="smooth"
:(the default) an image plot showing a smooth function, obtained by applying kernel smoothing to the exact leverage values;
what="nearest"
:an image plot showing a piecewise-constant function, obtained by taking the exact leverage value at the nearest quadrature point;
what="exact"
:a symbol plot showing the exact values of leverage as circles, centred at the quadrature points, with diameters proportional to leverage.
The pixel images are already contained in the object x
and were computed by leverage.ppm
;
the resolution of these images is controlled
by arguments to leverage.ppm
.
Same as for plot.im
, contour.im
and persp.im
respectively.
.
Baddeley, A., Chang, Y.M. and Song, Y. (2013) Leverage and influence diagnostics for spatial point process models. Scandinavian Journal of Statistics 40, 86–104.
leverage.ppm
.
if(offline <- !interactive()) op <- spatstat.options(npixel=32, ndummy.min=16)
X <- rpoispp(function(x,y) { exp(3+3*x) })
fit <- ppm(X ~x+y)
lef <- leverage(fit)
plot(lef)
contour(lef)
persp(lef)
if(offline) spatstat.options(op)
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