An object of class "influence.ppm" contains the values of the
likelihood influence for a point process model, computed by
influence.ppm. This is effectively a marked point
pattern obtained by marking each of the original data points
with its likelihood influence.
This function extracts a designated subset of the influence values,
either as another influence object, or as a vector of numeric values.
The function [.influence.ppm is a method for [ for the
class "influence.ppm". The argument i should be
an index applicable to a point pattern. It may be either
a spatial window (object of class "owin")
or a sequence index.
The result will be another influence object
(of class influence.ppm).
To extract the influence values as a numeric vector,
use marks(as.ppp(x)).