gdistance (version 1.1-2)

sumT: Summing transition objects

Description

Special methods to sum Transition objects

Usage

sumT(transition1, transition2)

Arguments

transition1

TransitionLayer object

transition2

TransitionLayer object

Value

• Transition object containing conductance values.

Details

This function is meant to sum Transition objects taking the resistance values instead of the conductance values. In other words, the function calculates the reciprocal of the summed reciprocals. If matrixValues(tr) is equal to dQuote{conductance} the reciprocal of the values is taken (1 / conductance), if it is equal to dQuote{resistance}, the values are used. Zero values are ignored. To treat a Transition object as containing resistance values instead of conductance values, use matrixValues(tr)<-"resistance".

Examples

#Create a new raster and set all its values to unity.
  raster <- raster(nrows=18, ncols=36) 
  raster <- setValues(raster,rep(1,ncell(raster)))

  #Create TransitionLayer objects
  tr1 <- transition(raster,mean,4)
  tr2 <- tr1
  matrixValues(tr1)
  
  #Set one to resistance
  matrixValues(tr2) <- "resistance"
  
  #Sum the two objects
  sumT(tr1,tr2)