sym_nuni_ln {noisemodel}

Symmetric non-uniform label noise

Description

Introduction of Symmetric non-uniform label noise into a classification dataset.

Usage

## Default S3 method:
sym_nuni_ln(x, y, level, tramat, sortid = TRUE, ...)

## S3 method for class 'formula'
sym_nuni_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.

tramat

a double matrix with the values of the transition matrix.

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 non-uniform label noise randomly selects (level·100)% of the samples in the dataset with independence of their class. Then, the labels of these samples are randomly replaced by other different ones according to the probabilities given in the transition matrix tramat. For details about the structure of the transition matrix, see Kang et al. (2021).

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

J. Kang, R. Fernandez-Beltran, P. Duan, X. Kang, and A. J. Plaza. Robust normalized softmax loss for deep metric learning-based characterization of remote sensing images with label noise. IEEE Transactions on Geoscience and Remote Sensing, 59(10):8798-8811, 2021. doi:10.1109/TGRS.2020.3042607.

See Also

sym_adj_ln, sym_dran_ln, print.ndmodel, summary.ndmodel, plot.ndmodel

Examples

# load the dataset
data(iris2D)

# usage of the default method
set.seed(9)
tramat <- matrix(data = c(0.9, 0.03, 0.07, 0.03, 0.9, 0.07, 0.03, 0.07, 0.9), 
                 nrow = 3, ncol = 3, byrow = TRUE)
outdef <- sym_nuni_ln(x = iris2D[,-ncol(iris2D)], y = iris2D[,ncol(iris2D)], 
                     level = 0.1, tramat = tramat)

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

# usage of the method for class formula
set.seed(9)
outfrm <- sym_nuni_ln(formula = Species ~ ., data = iris2D, level = 0.1, tramat = tramat)

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