EWMethod {FuzzyResampling}

E(xpected value)W(idth) resampling method for triangular and trapezoidal fuzzy numbers

Description

EWMethod returns the secondary (bootstrapped) sample and uses the resampling scheme which does not change the expected values and widths of the fuzzy variables from the initial sample (the EW method, see (Grzegorzewski et al, 2020)).

Usage

EWMethod(initialSample, b = n, increases = FALSE)

Arguments

initialSample

Initial sample of triangular or trapezoidal fuzzy numbers.

b

The number of fuzzy values in the resampled (secondary) sample. If this parameter is not specified, the number of values in the initial sample is used. The parameter should be integer value more than 0.

increases

If TRUE is used, then the initial sample should consist of the fuzzy numbers in the form: left increment of the support, left end of the core, right end of the core, right increment of the support. Otherwise, the default value FALSE is used and the fuzzy numbers should be given in the form: left end of the support, left end of the core, right end of the core, right end of the support.

Details

The initial sample should consist of triangular or trapezoidal fuzzy numbers, given as a single vector or a whole matrix. In each row, there should be a single fuzzy number in one of the forms:

1. left end of the support, left end of the core, right end of the core, right end of the support, or

2. left increment of the support, left end of the core, right end of the core, right increment of the support.

In this second case, the parameter increases=TRUE has to be used.

The resampling procedure produces b fuzzy values. During the first step, the fuzzy value from the initial sample is randomly chosen (with repetition). Then the new fuzzy variable, which preserves the expected value and width of the old one, is randomly created. If the parameter b is not specified, it is equal to the length of the initial sample. The output is given in the same form as the initial sample.

Value

This function returns matrix with b rows of double values. In each row, there is a single resampled fuzzy number. These fuzzy numbers have the same form as the values from the initial sample depending on the provided parameter increases.

References

Grzegorzewski, P., Hryniewicz, O., Romaniuk, M. (2020) Flexible resampling for fuzzy data International Journal of Applied Mathematics and Computer Science, 30 (2), pp. 281-297

See Also

ClassicalBootstrap, VAMethod for the VA method, VAFMethod for the VAF method, VAAMethod for the VAA method, DMethod for the d method, WMethod for the w method

Other resampling functions: ClassicalBootstrap(), DMethod(), VAAMethod(), VAFMethod(), VAMethod(), WMethod()

Examples

# prepare some fuzzy numbers (first type of the initial sample)

fuzzyValues <- matrix(c(0.25,0.5,1,1.25,0.75,1,1.5,2.2,-1,0,0,2),
ncol = 4,byrow = TRUE)

# generate the secondary sample using the EW method

set.seed(12345)

EWMethod(fuzzyValues)

EWMethod(fuzzyValues,b=4)

# prepare some fuzzy numbers (second type of the initial sample)

fuzzyValuesInc <- matrix(c(0.25,0.5,1,0.25,0.25,1,1.5,0.7,1,0,0,2),
ncol = 4,byrow = TRUE)

# generate the secondary sample using the EW method

EWMethod(fuzzyValuesInc,increases = TRUE)

EWMethod(fuzzyValuesInc,b=4,increases = TRUE)