Mark of Nearest Neighbour
Given a marked point pattern dataset X
this function computes, for each desired location y,
the mark attached to the nearest neighbour of y in X.
The desired locations y can be either a pixel grid
or the point pattern X itself.
nnmark(X, ..., k = 1, at=c("pixels", "points"))X |
A marked point pattern (object of class |
... |
Arguments passed to |
k |
Single integer. The |
at |
String specifying whether to compute the values
at a grid of pixel locations ( |
Given a marked point pattern dataset X
this function computes, for each desired location y,
the mark attached to the point of X that is nearest
to y. The desired locations y can be either a pixel grid
or the point pattern X itself.
The argument X must be a marked point pattern (object
of class "ppp", see ppp.object).
The marks are allowed to be a vector or a data frame.
If at="points", then for each point in X,
the algorithm finds the nearest other point in X,
and extracts the mark attached to it.
The result is a vector or data frame containing the marks
of the neighbours of each point.
If at="pixels" (the default), then for each pixel
in a rectangular grid, the algorithm finds the nearest point in X,
and extracts the mark attached to it.
The result is an image or a list of images containing the marks
of the neighbours of each pixel.
The pixel resolution is controlled by the arguments ...
passed to as.mask.
If the argument k is given, then the k-th nearest
neighbour will be used.
If X has a single column of marks:
If at="pixels" (the default), the result is
a pixel image (object of class "im").
The value at each pixel is the mark attached
to the nearest point of X.
If at="points", the result is a vector or factor
of length equal to the number of points in X.
Entries are the mark values of the
nearest neighbours of each point of X.
If X has a data frame of marks:
If at="pixels" (the default), the result is a named list of
pixel images (object of class "im"). There is one
image for each column of marks. This list also belongs to
the class "solist", for which there is a plot method.
If at="points", the result is a data frame
with one row for each point of X,
Entries are the mark values of the
nearest neighbours of each point of X.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
Rolf Turner r.turner@auckland.ac.nz
and Ege Rubak rubak@math.aau.dk
plot(nnmark(ants)) v <- nnmark(ants, at="points") v[1:10] plot(nnmark(finpines)) vf <- nnmark(finpines, at="points") vf[1:5,]
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