Extract.ppx

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Extract Subset of Multidimensional Point Pattern

Extract a subset of a multidimensional point pattern.

Keywords
manip, spatial
Usage
# S3 method for ppx
[(x, i, drop=FALSE, ...)
Arguments
x

A multidimensional point pattern (object of class "ppx").

i

Subset index. A valid subset index in the usual R sense, indicating which points should be retained; or a spatial domain of class "boxx" or "box3".

drop

Logical value indicating whether to remove unused levels of the marks, if the marks are a factor.

Ignored.

Details

This function extracts a designated subset of a multidimensional point pattern.

The function [.ppx is a method for [ for the class "ppx". It extracts a designated subset of a point pattern. The argument i may be either

• a subset index in the usual R sense: either a numeric vector of positive indices (identifying the points to be retained), a numeric vector of negative indices (identifying the points to be deleted) or a logical vector of length equal to the number of points in the point pattern x. In the latter case, the points (x$x[i], x$y[i]) for which subset[i]=TRUE will be retained, and the others will be deleted.

• a spatial domain of class "boxx" or "box3". Points falling inside this region will be retained.

The argument drop determines whether to remove unused levels of a factor, if the point pattern is multitype (i.e. the marks are a factor) or if the marks are a data frame or hyperframe in which some of the columns are factors.

Use the function unmark to remove marks from a marked point pattern.

Value

A multidimensional point pattern (of class "ppx").

ppx

• [.ppx
Examples
# NOT RUN {
df <- data.frame(x=runif(4),y=runif(4),z=runif(4))
X <- ppx(data=df, coord.type=c("s","s","t"))
X[-2]
# }
Documentation reproduced from package spatstat, version 1.57-1, License: GPL (>= 2)

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