This technique analyses simulation results generated through sampling using the eFAST approach (extended Fourier Amplitude Sampling Test). This perturbs the value of all parameters at the same time, with the aim of partitioning the variance in simulation output between input parameters. Values for each parameter are chosen using fourier frequency curves through a parameters potential range of values. A selected number of values are selected from points along the curve. Though all parameters are perturbed simultaneously, the method does focus on one parameter of interest in turn, by giving this a very different sampling frequency to that assigned to the other parameters. Thus for each parameter of interest in turn, a sampling frequency is assigned to each parameter and values chosen at points along the curve. So a set of simulation parameters then exists for each parameter of interest. As this is the case, this method can be computationally expensive, especially if a large number of samples is taken on the parameter search curve, or there are a large number of parameters. On top of this, to ensure adequate sampling each curve is also resampled with a small adjustment to the frequency, creating more parameter sets on which the simulation should be run. This attempts to limit any correlations and limit the effect of repeated parameter value sets being chosen. Samples are output to CSV file, one per parameter/curve pairing
efast_generate_sample(FILEPATH, NUMCURVES, NUMSAMPLES, PARAMETERS, PMIN,
PMAX, write_csv = TRUE, return_sample = FALSE)Directory where the parameter samples should be output to
The number of 'resamples' to perform (see eFAST documentation) - recommend using at least 3
The number of parameter subsets to generate - should be at least 65 for eFAST
Array containing the names of the parameters of which parameter samples will be generated. For eFAST, remember to add a parameter named 'Dummy'
Array containing the minimum value that should be used for each parameter and the dummy. Sets a lower bound on sampling space
Array containing the maximum value that should be used for each parameter and the dummy. Sets an upper bound on sampling space
Whether the sample should be output to CSV file. Should be true unless using spartan-db
Whether the complete sample should be returned as an R object. Used by spartan db and added to the database