params and P access the parameter slot in the simList. params has a replace method, so can be used to update a parameter value. P is a concise way to access parameters within a module. It works more like a namespaced function in the sense that the module from which it is called is the default place it will look for the parameter. To access a parameter from within a module, you can use P(sim)$paramName instead of params(sim)$moduleName$paramName params(sim) # S4 method for .simList params(sim) params(sim) <- value # S4 method for .simList params(sim) <- value P(sim, module, param) parameters(sim, asDF = FALSE) # S4 method for .simList parameters(sim, asDF = FALSE) ## Arguments sim A simList object from which to extract element(s) or in which to replace element(s). The object to be stored at the slot. Optional character string indicating which module params should come from. Optional character string indicating which parameter to choose. Logical. For parameters, if TRUE, this will produce a single data.frame of all model parameters. If FALSE, then it will return a data.frame with 1 row for each parameter within nested lists, with the same structure as params. ## Value Returns or sets the value of the slot from the simList object. ## Note The differences between P, params and being explicit with passing arguments are mostly a question of speed and code compactness. The computationally fastest way to get a parameter is to specify moduleName and parameter name, as in: P(sim, "moduleName", "paramName") (replacing moduleName and paramName with your specific module and parameter names), but it is more verbose than P(sim)$paramName. Note: the important part for speed (e.g., 2-4x faster) is specifying the moduleName. Specifying the parameter name is <5

SpaDES.core-package, specifically the section 1.2.1 on Simulation parameters.

Other functions to access elements of a simList object: .addDepends, doEvent.checkpoint, envir, events, globals, inputs, ls.simList, ls.str.simList, modules, objs, packages, paths, progressInterval, times

## Examples

# NOT RUN {
modules <- list("randomLandscapes")
paths <- list(modulePath = system.file("sampleModules", package = "SpaDES.core"))
mySim <- simInit(modules = modules, paths = paths,
params = list(.globals = list(stackName = "landscape")))
parameters(mySim)

# }