This method updates the rates of a species.
Examples
# set the seed of the random number generator
set.seed(0)
# create a simulation
sim <- SpatialSimulation()
sim$add_mutant(name = "A",
epigenetic_rates = c("+-" = 0.01, "-+" = 0.01),
growth_rates = c("+" = 0.2, "-" = 0.08),
death_rates = c("+" = 0.1, "-" = 0.01))
# Set the death and epigenetic switch rates of "A-" to 0
sim$update_rates("A-", c(switch=0, death=0))