optimization: Multiple model runs and function factories for optimization routines

Description

Function factories to generate functions to be used in model calibration, uncertainty or sensitivity analysis.

Usage

multiple_runs(parMatrix, x,
              meteo, latitude,
              elevation = NA, slope = NA, aspect = NA, 
              summary_function = NULL, args = NULL, 
              verbose = TRUE)
optimization_function(parNames, x, 
                      meteo, latitude,
                      elevation = NA, slope = NA, aspect = NA, 
                      summary_function, args= NULL)
optimization_evaluation_function(parNames, x, 
                      meteo, latitude,
                      elevation = NA, slope = NA, aspect = NA, 
                      measuredData, type = "SWC", cohorts = NULL, 
                      temporalResolution = "day",
                      metric = "loglikelihood")
optimization_multicohort_function(cohortParNames, cohortNames, x, 
                      meteo, latitude, 
                      otherParNames = NULL,
                      elevation = NA, slope = NA, aspect = NA, 
                      summary_function, args= NULL)
optimization_evaluation_multicohort_function(cohortParNames, cohortNames, x, 
                      meteo, latitude,
                      otherParNames = NULL,
                      elevation = NA, slope = NA, aspect = NA, 
                      measuredData, type = "SWC", cohorts = cohortNames,
                      temporalResolution = "day", 
                      metric = "loglikelihood")

Value

Function multiple_runs returns a list, whose elements are either the result of calling simulation models or the result of calling summary_function afterwards.

Function optimization_function returns a function whose parameters are parameter values and whose return is a prediction scalar (e.g. total transpiration).

Function optimization_evaluation_function returns a function whose parameters are parameter values and whose return is an evaluation metric (e.g. loglikelihood of the data observations given model predictions). If evaluation data contains information for different cohorts (e.g. plant water potentials or transpiration rates) then the evaluation is performed for each cohort and the metrics are averaged.

Function optimization_multicohorts_function returns a function whose parameters are parameter values and whose return is a prediction scalar (e.g. total transpiration). The difference with optimization_function is that multiple cohorts are set to the same parameter values.

Function optimization_evaluation_multicohort_function returns a function whose parameters are parameter values and whose return is an evaluation metric (e.g. loglikelihood of the data observations given model predictions). If evaluation data contains information for different cohorts (e.g. plant water potentials or transpiration rates) then the evaluation is performed for each cohort and the metrics are averaged. The difference with optimization_evaluation_function is that multiple cohorts are set to the same parameter values.

Arguments

parMatrix: A matrix of parameter values with runs in rows and parameters in columns. Column names should follow parameter modification naming rules (see examples and naming rules in modifyInputParams).
parNames: A string vector of parameter names (see examples and naming rules in modifyInputParams).
x: An object of class spwbInput or growthInput.
meteo, latitude, elevation, slope, aspect: Additional parameters to simulation functions spwb or growth.
verbose: A flag to indicate extra console output.
measuredData: A data frame with observed/measured values. Dates should be in row names, whereas columns should be named according to the type of output to be evaluated (see details).
type: A string with the kind of model output to be evaluated. Accepted values are "SWC" (soil moisture content), "REW" relative extractable water, "ETR" (total evapotranspiration), "E" (transpiration per leaf area), "LFMC" (live fuel moisture content) and "WP" (plant water potentials).
cohorts: A string or a vector of strings with the cohorts to be compared (e.g. "T1_68"). If several cohort names are provided, the function optimization_cohorts_function evaluates the performance for each one and provides the mean value. If NULL results for the first cohort will be evaluated.
temporalResolution: A string to indicate the temporal resolution of the model evaluation, which can be "day", "week", "month" or "year". Observed and modelled values are aggregated temporally (using either means or sums) before comparison.
metric: An evaluation metric (see evaluation_metric).
summary_function: A function whose input is the result of spwb or growth. The function must return a numeric scalar in the case of optimization_function, but is not restricted in the case of multiple_runs.
args: A list of additional arguments of optimization_function.
cohortParNames: A string vector of vegetation parameter names for cohorts (e.g. 'Z95' or 'psiExtract').
cohortNames: A string vector of cohort names. All cohorts will be given the same parameter values for each parameter in 'cohortParNames'.
otherParNames: A string vector of parameter names (see examples and naming rules in modifyInputParams) for non-vegetation parameters (i.e. control parameters and soil parameters).

Author

Miquel De Cáceres Ainsa, CREAF

Details

See evaluation for details regarding how to specify measured data.

Functions produced by these function factories should be useful for sensitivity analyses using package 'sensitivity'.

Parameter naming (i.e. parNames) should follow the rules specified in section details of modifyInputParams. The exception to the naming rules applies when multiple cohorts are to be modified to the same values with functions optimization_multicohort_function and optimization_evaluation_multicohort_function. Then, only a vector of parameter names is supplied for cohortParNames.

Examples

Run this code

if (FALSE) {
#Load example daily meteorological data
data(examplemeteo)

#Load example plot plant data
data(exampleforestMED)

#Default species parameterization
data(SpParamsMED)

#Initialize soil with default soil params (4 layers)
examplesoil = soil(defaultSoilParams(4))

#Initialize control parameters
control = defaultControl("Granier")

#Initialize input
x1 = forest2spwbInput(exampleforestMED,examplesoil, SpParamsMED, control)

# Cohort name for Pinus halepensis
PH_coh = paste0("T1_", SpParamsMED$SpIndex[SpParamsMED$Name=="Pinus halepensis"])
PH_coh 

#Parameter names of interest
parNames = c(paste0(PH_coh,"/Z50"), paste0(PH_coh,"/Z95"))

#Specify parameter matrix
parMatrix <- cbind(c(200,300), c(500,1000))
colnames(parMatrix) <- parNames

#Define a summary function as the total transpiration over the simulated period
sf<-function(x) {sum(x$WaterBalance$Transpiration, na.rm=TRUE)}

#Perform two runs and evaluate the summary function
multiple_runs(parMatrix, 
              x1, examplemeteo, latitude = 42, elevation = 100,
              summary_function = sf)
              
#Load observed data (in this case the same simulation results with some added error)  
# Generate a prediction function for total transpiration over the simulated period
# as a function of parameters "Z50" and "Z95" for Pinus halepensis cohort 
of<-optimization_function(parNames = parNames,
                          x = x1,
                          meteo = examplemeteo, 
                          latitude = 41.82592, elevation = 100,
                          summary_function = sf)

# Evaluate for the values of the parameter matrix
of(parMatrix[1, ])
of(parMatrix)


# Generate a loglikelihood function for soil water content
# as a function of parameters "Z50" and "Z95" for Pinus halepensis cohort 
data(exampleobs)
oef<-optimization_evaluation_function(parNames = parNames,
                x = x1,
                meteo = examplemeteo, latitude = 41.82592, elevation = 100,
                measuredData = exampleobs, type = "SWC", 
                metric = "loglikelihood")

# Loglikelihood for the values of the parameter matrix
oef(parMatrix[1, ])
oef(parMatrix)
}

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