multiplicity.Spatial {surveillance}

Count Number of Instances of Points

Description

The generic function multiplicity defined in spatstat.geom is intended to count the number of duplicates of each element of an object. spatstat.geom already offers methods for point patterns, matrices and data frames, and here we add a method for Spatial objects from the sp package. It is a wrapper for the default method, which effectively computes the distance matrix of the points, and then just counts the number of zeroes in each row.

Usage

## S3 method for class 'Spatial'
multiplicity(x)

Arguments

x

a "Spatial" object (we only need a coordinates-method), e.g. of class "SpatialPoints".

Value

an integer vector containing the number of instances of each point of the object.

See Also

multiplicity in package spatstat.geom. See the Examples of the hagelloch data for a specific use of multiplicity.

Examples

foo <- SpatialPoints(matrix(c(1,2,
                              2,3,
                              1,2,
                              4,5), 4, 2, byrow=TRUE))
multiplicity(foo)

# the following function determines the multiplicities in a matrix
# or data frame and returns unique rows with appended multiplicity
countunique <- function(x) unique(cbind(x, count=multiplicity(x)))
countunique(coordinates(foo))