Generic function to test whether a given object (usually a point pattern or something related to a point pattern) has ``marks'' attached to the points.
is.marked(X, …)Object to be inspected
Other arguments.
Logical value, equal to TRUE if X is marked.
``Marks'' are observations attached to each point of a point pattern.
For example the longleaf dataset
contains the locations of trees, each tree being marked by its diameter;
the amacrine dataset gives the locations of cells
of two types (on/off) and the type of cell may be regarded as a mark attached
to the location of the cell.
Other objects related to point patterns, such as point process models, may involve marked points.
This function tests whether the object X
contains or involves marked points.
It is generic; methods are provided
for point patterns (objects of class "ppp")
and point process models (objects of class "ppm").