# Extract.lpp

0th

Percentile

##### Extract Subset of Point Pattern on Linear Network

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

Keywords
manip, spatial
##### Usage
## S3 method for class 'lpp':
[(x, i, j, ...)
##### Arguments
x
A point pattern on a linear network (object of class "lpp").
i
Subset index. A valid subset index in the usual Rsense, indicating which points should be retained
j
Spatial window (object of class "owin") delineating the region that should be retained.
...
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 Rsense: 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.

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

##### Value

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

lpp
# Chicago crimes data - remove cases of assault
chicago[marks(chicago) != "assault"]