If the way mizer calculates a fundamental rate entering the model is not flexible enough for you (for example if you need to introduce time dependence) then you can write your own functions for calculating that rate and use setRateFunction() to register it with mizer.

setRateFunction(params, rate, fun)

getRateFunction(params, rate)


other_params(params) <- value



A MizerParams object


Name of the rate for which a new function is to be set.


Name of the function to use to calculate the rate.


Values for other parameters


For setRateFunction(): An updated MizerParams object

For getRateFunction(): The name of the registered rate function for the requested rate, or the list of all rate functions if called without rate argument.

For other_params(): A named list with all the parameters for which you have set values.


At each time step during a simulation with the project() function, mizer needs to calculate the instantaneous values of the various rates. By default it calls the mizerRates() function which creates a list with the following components:

For each of these you can substitute your own function. So for example if you have written your own function for calculating the total mortality rate and have called it myMort and have a mizer model stored in a MizerParams object called params that you want to run with your new mortality rate, then you would call

params <- setRateFunction(params, "Mort", "myMort")

In general if you want to replace a function mizerSomeRateFunc() with a function myVersionOfThis() you would call

params <- setRateFunction(params, "SomeRateFunc", "myVersionOfThis")

In some extreme cases you may need to swap out the entire mizerRates() function for your own function called myRates(). That you can do with

params <- setRateFunction(params, "Rates", "myRates")

Your new rate functions may need their own model parameters. These you can store in other_params(params). For example

other_params(params)$my_param <- 42

Note that your own rate functions need to be defined in the global environment or in a package. If they are defined within a function then mizer will not find them.