nnmark

0th

Percentile

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.

Keywords
methods, smooth, spatial
Usage
nnmark(X, ..., k = 1, at=c("pixels", "points"))
Arguments
X
A marked point pattern (object of class "ppp").
...
Arguments passed to as.mask to determine the pixel resolution.
k
Single integer. The kth nearest data point will be used.
at
String specifying whether to compute the values at a grid of pixel locations (at="pixels") or only at the points of X (at="points").
Details

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.

  • Ifat="points", then for each point inX, the algorithm finds the nearestotherpoint inX, and extracts the mark attached to it. The result is a vector or data frame containing the marks of the neighbours of each point.
  • Ifat="pixels"(the default), then for each pixel in a rectangular grid, the algorithm finds the nearest point inX, 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 toas.mask.

If the argument k is given, then the k-th nearest neighbour will be used.

Value

  • If X has a single column of marks:
    • Ifat="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 ofX.
    • Ifat="points", the result is a vector or factor of length equal to the number of points inX. Entries are the mark values of the nearest neighbours of each point ofX.
    If X has a data frame of marks:
    • Ifat="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.
    • Ifat="points", the result is a data frame with one row for each point ofX, Entries are the mark values of the nearest neighbours of each point ofX.

See Also

Smooth.ppp, marktable, nnwhich

Aliases
  • nnmark
Examples
plot(nnmark(ants))
  v <- nnmark(ants, at="points")
  v[1:10]
  plot(nnmark(finpines))
  vf <- nnmark(finpines, at="points")
  vf[1:5,]
Documentation reproduced from package spatstat, version 1.42-2, License: GPL (>= 2)

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