@@ -33,9 +33,10 @@ In this vignette, we use the **GR4J** model to illustrate the different optimiza
In particular, we assume that the R global environment contains input climate data, observed discharge and functions from the [Get Started](V01_get_started.html) vignette, as shown below.
Please note that the calibration period is defined in the `CreateRunOptions()` function .
@@ -54,15 +55,15 @@ Here we choose to minimize the root mean square error.
The change of the repository from the "real" parameter space to a "transformed" space ensures homogeneity of displacement in the different dimensions of the parameter space during the step-by-step procedure of the calibration algorithm of the model.
```{r, warning=FALSE, results='hide'}
OptimGR4J <- function(Param_Optim) {
```{r, warning=FALSE, results='hide', eval=FALSE}
OptimGR4J <- function(ParamOptim) {
## Transformation of the parameter set to real space
As can be seen below, the optimum performance criterion values (column *objective*) can differ from the global optimum value in many cases, resulting in various parameter sets.
```{r, warning=FALSE}
summary(df_port)
summary(parPORT)
```
The existence of several local minima illustrates the importance of defining an appropriate starting point or of using a multi-start strategy or a global optimization strategy.
airGR::TransfoParam_GR4J(ParamIn = optPORT$par , Direction = "TR"),
airGR::TransfoParam_GR4J(ParamIn = as.numeric(optDE$optim$bestmem), Direction = "TR"),
airGR::TransfoParam_GR4J(ParamIn = as.numeric(optPSO$par) , Direction = "TR"),
airGR::TransfoParam_GR4J(ParamIn = optMALS$sol , Direction = "TR")),
digits = 3))
parGLOB
```
<!-- This is an expected result because the response surface for quadratic performance criteria of the **GR4J** model is generally sufficiently well defined in the transformed parameter space to allow using a local optimization strategy instead of a more time consuming global optimization strategy. -->