scutr: undersample_tomek – R documentation

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undersample_tomek

Undersample a dataset by removing Tomek links.

Description

A Tomek link is a minority instance and majority instance that are each other's nearest neighbor. This function removes sufficient Tomek links that are an instance of cls to yield m instances of cls. If desired, samples are randomly discarded to yield m rows if insufficient Tomek links are in the data.

Usage

undersample_tomek(
  data,
  cls,
  cls_col,
  m,
  tomek = "minor",
  force_m = TRUE,
  dist_calc = "euclidean"
)

Arguments

`data`	Dataset to be undersampled.
`cls`	Majority class to be undersampled.
`cls_col`	Column in data containing class memberships.
`m`	Desired number of samples in undersampled dataset.
`tomek`	Definition used to determine if a point is considered a minority in the Tomek link definition. `minor`: Minor classes are all those with fewer than `m` instances. `diff`: Minor classes are all those that aren't `cls`.
`force_m`	If `TRUE`, uses random undersampling to discard samples if insufficient Tomek links are present to yield `m` rows of data.
`dist_calc`	Distance calculation method. See `dist()`.

Value

Undersampled dataframe containing only cls.

Examples

table(iris$Species)
undersamp <- undersample_tomek(iris, "setosa", "Species", 15, tomek = "diff", force_m = TRUE)
nrow(undersamp)
undersamp2 <- undersample_tomek(iris, "setosa", "Species", 15, tomek = "diff", force_m = FALSE)
nrow(undersamp2)

scutr

Balancing Multiclass Datasets for Classification Tasks

v0.1.2

MIT + file LICENSE

Authors

Keenan Ganz [aut, cre]

Initial release