Random Re-Labelling of Point Pattern
Randomly allocates marks to a point pattern, or permutes the existing marks, or resamples from the existing marks.
rlabel(X, labels=marks(X), permute=TRUE, group=NULL, ..., nsim=1, drop=TRUE)
X |
Point pattern (object of class |
labels |
Vector of values from which the new marks will be drawn at random. Defaults to the vector of existing marks. |
permute |
Logical value indicating whether to generate new marks
by randomly permuting |
group |
Optional. A factor, or other data dividing the points into groups. Random relabelling will be performed separately within each group. See Details. |
... |
Additional arguments passed to |
nsim |
Number of simulated realisations to be generated. |
drop |
Logical. If |
This very simple function allocates random marks to
an existing point pattern X. It is useful
for hypothesis testing purposes. (The function can also be applied
to line segment patterns.)
In the simplest case, the command rlabel(X) yields
a point pattern obtained from X by randomly permuting
the marks of the points.
If permute=TRUE, then labels should be a vector of
length equal to the number of points in X.
The result of rlabel will be a point pattern
with locations given by X and marks given by
a random permutation of labels (i.e. a random sample without
replacement).
If permute=FALSE, then labels may be a vector of
any length.
The result of rlabel will be a point pattern
with locations given by X and marks given by
a random sample from labels (with replacement).
The argument group specifies that the points are
divided into several different groups, and that the random labelling
shall be performed separately on each group.
The arguments group and ... are passed to
cut.ppp to determine the grouping. Thus group
could be a factor, or the name of a column of marks in
X, or a tessellation, or a factor-valued pixel image, etc.
If nsim = 1 and drop=TRUE,
a marked point pattern (of the same class as X).
If nsim > 1, a list of point patterns.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk.
marks<- to assign arbitrary marks.
amacrine
# Randomly permute the marks "on" and "off"
# Result always has 142 "off" and 152 "on"
Y <- rlabel(amacrine)
# randomly allocate marks "on" and "off"
# with probabilities p(off) = 0.48, p(on) = 0.52
Y <- rlabel(amacrine, permute=FALSE)
# randomly allocate marks "A" and "B" with equal probability
Y <- rlabel(cells, labels=factor(c("A", "B")), permute=FALSE)
# divide the window into tiles and
# randomly permute the marks within each tile
Z <- rlabel(amacrine, group=quadrats(Window(amacrine), 4, 3))Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.