sym_opt_ln {noisemodel}

Symmetric optimistic label noise

Description

Introduction of Symmetric optimistic label noise into a classification dataset.

Usage

## Default S3 method:
sym_opt_ln(x, y, level, levelH = 0.9, order = levels(y), sortid = TRUE, ...)

## S3 method for class 'formula'
sym_opt_ln(formula, data, ...)

Arguments

x

a data frame of input attributes.

y

a factor vector with the output class of each sample.

level

a double in [0,1] with the noise level to be introduced.

levelH

a double in (0.5, 1] with the noise level for higher classes (default: 0.9).

order

a character vector indicating the order of the classes (default: levels(y)).

sortid

a logical indicating if the indices must be sorted at the output (default: TRUE).

...

other options to pass to the function.

formula

a formula with the output class and, at least, one input attribute.

data

a data frame in which to interpret the variables in the formula.

Details

Symmetric optimistic label noise randomly selects (level·100)% of the samples in the dataset with independence of their class. In the optimistic case, the probability of a class i of being mislabeled as class j is higher for j > i in comparison to j < i. Thus, when noise for a certain class occurs, it is assigned to a random higher class with probability levelH and to a random lower class with probability 1-levelH. The order of the classes is determined by order.

Value

An object of class ndmodel with elements:

xnoise

a data frame with the noisy input attributes.

ynoise

a factor vector with the noisy output class.

numnoise

an integer vector with the amount of noisy samples per class.

idnoise

an integer vector list with the indices of noisy samples.

numclean

an integer vector with the amount of clean samples per class.

idclean

an integer vector list with the indices of clean samples.

distr

an integer vector with the samples per class in the original data.

model

the full name of the noise introduction model used.

param

a list of the argument values.

call

the function call.

Note

Noise model adapted from the papers in References.

References

R. C. Prati, J. Luengo, and F. Herrera. Emerging topics and challenges of learning from noisy data in nonstandard classification: a survey beyond binary class noise. Knowledge and Information Systems, 60(1):63–97, 2019. doi:10.1007/s10115-018-1244-4.

See Also

sym_usim_ln, sym_natd_ln, print.ndmodel, summary.ndmodel, plot.ndmodel

Examples

# load the dataset
data(iris2D)

# usage of the default method
set.seed(9)
outdef <- sym_opt_ln(x = iris2D[,-ncol(iris2D)], y = iris2D[,ncol(iris2D)], 
                     level = 0.1, order = c("virginica", "setosa", "versicolor"))

# show results
summary(outdef, showid = TRUE)
plot(outdef)

# usage of the method for class formula
set.seed(9)
outfrm <- sym_opt_ln(formula = Species ~ ., data = iris2D, 
                     level = 0.1, order = c("virginica", "setosa", "versicolor"))

# check the match of noisy indices
identical(outdef$idnoise, outfrm$idnoise)