R: Simulate hydromad models by parameter sampling.

simulate.hydromad {hydromad}

R Documentation

Simulate hydromad models by parameter sampling.

Description

Run many simulations by sampling within parameter ranges.

Usage

## S3 method for class 'hydromad'
simulate(object, nsim, seed, ...,
         sampletype = c("latin.hypercube", "random", "all.combinations"),
         FUN = NULL, objective = NULL, bind = !is.null(objective))

Arguments

`object`	a `hydromad` object (produced by the `hydromad()` function) that is not fully specified (i.e. so some parameter values are given as ranges).
`nsim`	number of parameter samples to run.
`seed`	optional random seed, for repeatability.
`...`	further arguments to `FUN`.
`sampletype`	sampling method; see `parameterSets`.
`FUN`	optional function to apply to each simulated model. Typical examples would be `objFunVal`, `summary` or `predict`.
`objective`	an objective function (or statistic function); this is just an argument to be passed on to `FUN`, which in this case defaults to `objFunVal` to calculate the statistic value from each model. It is treated as a special argument because it is cached before the simulation run for efficiency.
`bind`	to bind the result from `FUN` as one or more columns onto the matrix of parameter values, and return as a data frame.

Details

none yet.

Value

a list of results, where each element is named by its parameter set. The result also has an attribute "psets" which gives the parameter values used in each simulation (as a data frame).

If bind = TRUE, a data frame.

Author(s)

Felix Andrews felix@nfrac.org

Examples

data(Canning)
mod0 <- hydromad(Canning[1:500,], sma = "cwi")
sim0 <- simulate(mod0, nsim = 5, sampletype = "latin")
coef(sim0)
summary(sim0)

## plot the objective function surface over two parameters
mod1 <- update(mod0, routing = "armax", rfit = list("ls", order = c(2,1)))
sim1 <- simulate(mod1, 144, sampletype = "all", FUN = objFunVal,
          objective = ~ nseStat(Q, X, trans = sqrt))
levelplot(result ~ tw + f, sim1, cex = 2,
          panel = panel.levelplot.points,
          main = "R Squared (of sq.rt. data) over parameter space") +
layer_(panel.2dsmoother(...))

## dotty plots (list any number of parameters in formula)
xyplot(result ~ tw + f, sim1, outer = TRUE)

[Package hydromad version 0.9-18 Index]