Drop Unused Factor Levels in all Factor Columns

Usage

dropUnusedFactorLevels(data, dbg = TRUE)

Arguments

data: data frame in which to remove unused levels in all columns that are factors
dbg: if TRUE, debug messages are shown

Value

data with unused factors removed in all columns being factors

Examples

# Create an example data frame with two factor columns
data <- data.frame(
  id = 1:3, 
  factor_1 = factor(c("a", "b", "a"), levels = c("a", "b", "c")),
  factor_2 = factor(c("x", "x", "y"), levels = c("x", "y", "z")),
  no_factor = c("A", "B", "C"),
  stringsAsFactors = FALSE
)

# Review the structure of the data frame
str(data)
#> 'data.frame':	3 obs. of  4 variables:
#>  $ id       : int  1 2 3
#>  $ factor_1 : Factor w/ 3 levels "a","b","c": 1 2 1
#>  $ factor_2 : Factor w/ 3 levels "x","y","z": 1 1 2
#>  $ no_factor: chr  "A" "B" "C"

# Review the structure of the data frame with unused factors removed
str(dropUnusedFactorLevels(data))
#> Removing unused factors from data$factor_1 ... ok. (0.00 secs) 
#> Removing unused factors from data$factor_2 ... ok. (0.00 secs) 
#> 'data.frame':	3 obs. of  4 variables:
#>  $ id       : int  1 2 3
#>  $ factor_1 : Factor w/ 2 levels "a","b": 1 2 1
#>  $ factor_2 : Factor w/ 2 levels "x","y": 1 1 2
#>  $ no_factor: chr  "A" "B" "C"