Create a User-defined Parametric Growth Model

This constructor method allows to create user-defined functions that can be used as parametric models describing time-dependent growth of organisms.

Usage

growthmodel(x, pnames = NULL)

Arguments

x

a function with arguments times and parms, and returning a matrix with two columns time and y.

pnames

character vector with the names of the model parameters.

Details

Package growthrates has a plug-in architecture allowing user-defined growth models of the following form:

  identifier <- function(time, parms) {
    ... content of function here ...
    return(as.matrix(data.frame(time=time, y=y)))
  }

where time is a numeric vector and parms a named, non-nested list of model parameters. The constructor function growthmodel is used to attach the names of the parameters as an optional attribute.

See also

Other growth models: grow_baranyi(), grow_exponential(), grow_gompertz(), grow_gompertz2(), grow_huang(), grow_logistic(), grow_richards(), ode_genlogistic(), ode_twostep()

Examples

test <- function(time, parms) {
  with(as.list(parms), {
    y <- (K * y0) / (y0 + (K - y0) * exp(-mumax * time)) + y_shift
    return(as.matrix(data.frame(time=time, y=y)))
 })
}

mygrowthmodel <- growthmodel(test, c("y0", "mumax", "K", "y_shift"))