is.marked.ppp: Test Whether A Point Pattern is Marked

Description

Tests whether a point pattern has ``marks'' attached to the points.

Usage

## S3 method for class 'ppp':
is.marked(X, na.action="warn", \dots)

Arguments

Point pattern (object of class "ppp")

na.action

String indicating what to do if NA values are encountered amongst the marks. Options are "warn", "fatal" and "ignore".

...

Ignored.

Value

Logical value, equal to TRUE if X is a marked point pattern.

Details

``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.

This function tests whether the point pattern X contains or involves marked points. It is a method for the generic function is.marked.

The argument na.action determines what action will be taken if the point pattern has a vector of marks but some or all of the marks are NA. Options are "fatal" to cause a fatal error; "warn" to issue a warning and then return TRUE; and "ignore" to take no action except returning TRUE.

Examples

Run this code

data(cells)
   is.marked(cells)  #FALSE
   data(longleaf)
   is.marked(longleaf) #TRUE