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Lump uncommon factor levels together into "other"

Source: R/lump.R
fct_lump_helpers.Rd

A family of functions to lump together levels based on different criteria:

  • fct_lump_min(): lumps levels that appear fewer than min times.

  • fct_lump_prop(): lumps levels that appear in fewer than (or equal to) prop * n times.

  • fct_lump_n() lumps all levels except for the n most frequent (or least frequent if n < 0)

  • fct_lump_lowfreq() lumps together the least frequent levels, ensuring that "other" is still the smallest level.

Usage

fct_lump_min(f, min, w = NULL, other_level = "Other")

fct_lump_prop(f, prop, w = NULL, other_level = "Other")

fct_lump_n(
  f,
  n,
  w = NULL,
  other_level = "Other",
  ties.method = c("min", "average", "first", "last", "random", "max")
)

fct_lump_lowfreq(f, w = NULL, other_level = "Other")

Arguments

f

A factor (or character vector).

min

Preserve levels that appear at least min number of times.

w

An optional numeric vector giving weights for frequency of each value (not level) in f.

other_level

Value of level used for "other" values. Always placed at end of levels.

prop

Positive prop lumps values which do not appear at least prop of the time. Negative prop lumps values that do not appear at most -prop of the time.

n

Positive n preserves the most common n values. Negative n preserves the least common -n values. If there are ties, you will get at least abs(n) values.

ties.method

A character string specifying how ties are treated. See rank() for details.

See also

fct_other() to convert specified levels to other.

Examples

x <- factor(rep(LETTERS[1:9], times = c(40, 10, 5, 27, 1, 1, 1, 1, 1)))
x |> table()
#> x
#>  A  B  C  D  E  F  G  H  I 
#> 40 10  5 27  1  1  1  1  1 
x |>
  fct_lump_n(3) |>
  table()
#> 
#>     A     B     D Other 
#>    40    10    27    10 
x |>
  fct_lump_prop(0.10) |>
  table()
#> 
#>     A     B     D Other 
#>    40    10    27    10 
x |>
  fct_lump_min(5) |>
  table()
#> 
#>     A     B     C     D Other 
#>    40    10     5    27     5 
x |>
  fct_lump_lowfreq() |>
  table()
#> 
#>     A     D Other 
#>    40    27    20