Extract.lpp: Extract Subset of Point Pattern on Linear Network In spatstat.linnet: Linear Networks Functionality of the 'spatstat' Family

Description

Extract a subset of a point pattern on a linear network.

Usage

 ```1 2``` ``` ## S3 method for class 'lpp' x[i, j, drop=FALSE, ..., snip=TRUE] ```

Arguments

 `x` A point pattern on a linear network (object of class `"lpp"`). `i` Subset index. A valid subset index in the usual R sense, indicating which points should be retained. `j` Spatial window (object of class `"owin"`) delineating the region that should be retained. `drop` Logical value indicating whether to remove unused levels of the marks, if the marks are a factor. `snip` Logical. If `TRUE` (the default), segments of the network which cross the boundary of the window `j` will be cut by the boundary. If `FALSE`, these segments will be deleted. `...` Ignored.

Details

This function extracts a designated subset of a point pattern on a linear network.

The function `[.lpp` is a method for `[` for the class `"lpp"`. It extracts a designated subset of a point pattern. The argument `i` should be 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.

The argument `j`, if present, should be a spatial window. The pattern inside the region will be retained. Line segments that cross the boundary of the window are deleted in the current implementation.

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.

The argument `snip` specifies what to do with segments of the network which cross the boundary of the window `j`. If `snip=FALSE`, such segments are simply deleted. If `snip=TRUE` (the default), such segments are cut into pieces by the boundary of `j`, and those pieces which lie inside the window `ji` are included in the resulting network.

Use `unmark` to remove all the marks in a marked point pattern, and `subset.lpp` to remove only some columns of marks.

Value

A point pattern on a linear network (of class `"lpp"`).

Author(s)

and \rolf

`lpp`, `subset.lpp`
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ``` # Chicago crimes data - remove cases of assault chicago[marks(chicago) != "assault"] # equivalent to subset(chicago, select=-assault) # spatial window subset B <- owin(c(350, 700), c(600, 1000)) plot(chicago) plot(B, add=TRUE, lty=2, border="red", lwd=3) op <- par(mfrow=c(1,2), mar=0.6+c(0,0,1,0)) plot(B, main="chicago[B, snip=FALSE]", lty=3, border="red") plot(chicago[, B, snip=FALSE], add=TRUE) plot(B, main="chicago[B, snip=TRUE]", lty=3, border="red") plot(chicago[, B, snip=TRUE], add=TRUE) par(op) ```