traps.info: Detector Attributes

Description

Extract or replace attributes of an object of class 'traps'.

Usage

polyID(object)
polyID(object) <- value
transectID(object)
transectID(object) <- value
searcharea(object)
searcharea(object) <- value
transectlength(object)

Arguments

object

a 'traps' object

value

replacement value (see Details)

Value

polyID - a factor with one level per polygon. searcharea - numeric value of quadrat area or polygon areas, in hectares. transectlength - numeric value of transect lengths, in metres.

Details

The 'polyID' and 'transectID' functions assign and extract the attribute of a 'traps' object that relates vertices (rows) to particular polygons or transects. The replacement value should be a factor of length equal to nrow(object). The 'searcharea' attribute of a 'quadratbinary' or 'quadratcount' traps object is the area in hectares searched at each detector point (quadrat). Usually, this is the area of a rectangular pixel determined by the detector spacing (spacex, spacey). Replacement creates square pixels with dimensions spacex = spacey = value^0.5 * 100. The 'searcharea' of a 'polygon' traps object is a vector of the areas of the component polygons. This is a read-only value (i.e. 'searcharea<-' does not apply). The 'transectlength' of a 'transect' traps object is a vector of the lengths of the component transects in metres. This is a read-only value.

Examples

Run this code

## default is a single polygon
temp <- make.grid(detector = 'polygon', hollow = TRUE)
polyID(temp)
plot(temp)

## split in two
temp <- make.grid(detector = 'polygon', hollow = TRUE)
polyID(temp) <- factor(rep(c(1,2),rep(10,2)))
plot(temp)