NoiseFiltersR (version 0.1.0)

GE: Generalized Edition

Description

Similarity-based filter for removing or repairing label noise from a dataset as a preprocessing step of classification. For more information, see 'Details' and 'References' sections.

Usage

"GE"(formula, data, ...)
"GE"(x, k = 5, kk = ceiling(k/2), classColumn = ncol(x), ...)

Arguments

formula

A formula describing the classification variable and the attributes to be used.

data, x

Data frame containing the tranining dataset to be filtered.

...

Optional parameters to be passed to other methods.

k

Number of nearest neighbors to be considered.

kk

Minimum size for local majority class in order to relabel an instance.

classColumn

positive integer indicating the column which contains the (factor of) classes. By default, the last column is considered.

Value

An object of class filter, which is a list with seven components:

• cleanData is a data frame containing the filtered dataset.
• remIdx is a vector of integers indicating the indexes for removed instances (i.e. their row number with respect to the original data frame).
• repIdx is a vector of integers indicating the indexes for repaired/relabelled instances (i.e. their row number with respect to the original data frame).
• repLab is a factor containing the new labels for repaired instances.
• parameters is a list containing the argument values.
• call contains the original call to the filter.
• extraInf is a character that includes additional interesting information not covered by previous items.

Details

GE is a generalization of ENN that integrates the possibility of 'repairing' or 'relabeling' instances rather than only 'removing'. For each instance, GE considers its k-1 neighbors and the instance itself. If there are at least kk examples from the same class, the instance is relabeled with that class (which could be its own). Otherwise, it is removed.

References

Koplowitz J., Brown T. A. (1981): On the relation of performance to editing in nearest neighbor rules. Pattern Recognition, 13(3), 251-255.

Examples

# Next example is not run in order to save time
## Not run: 
# data(iris)
# out <- GE(iris)
# summary(out, explicit = TRUE)
# # We check that the process was correct
# irisCopy <- iris
# irisCopy[out$repIdx,5] <- out$repLab
# cleanData <- irisCopy[setdiff(1:nrow(iris),out$remIdx),]
# identical(out$cleanData,cleanData)
# ## End(Not run)