This is a generalisation of stats::relevel() that allows you to move any
number of levels to any location.
Arguments
- .f
A factor (or character vector).
- ...
Either a function (or formula), or character levels.
A function will be called with the current levels as input, and the return value (which must be a character vector) will be used to relevel the factor.
Any levels not mentioned will be left in their existing order, by default after the explicitly mentioned levels. Supports tidy dots.
- after
Where should the new values be placed?
Examples
f <- factor(c("a", "b", "c", "d"), levels = c("b", "c", "d", "a"))
fct_relevel(f)
#> [1] a b c d
#> Levels: b c d a
fct_relevel(f, "a")
#> [1] a b c d
#> Levels: a b c d
fct_relevel(f, "b", "a")
#> [1] a b c d
#> Levels: b a c d
# Move to the third position
fct_relevel(f, "a", after = 2)
#> [1] a b c d
#> Levels: b c a d
# Relevel to the end
fct_relevel(f, "a", after = Inf)
#> [1] a b c d
#> Levels: b c d a
fct_relevel(f, "a", after = 3)
#> [1] a b c d
#> Levels: b c d a
# Relevel with a function
fct_relevel(f, sort)
#> [1] a b c d
#> Levels: a b c d
fct_relevel(f, sample)
#> [1] a b c d
#> Levels: a c b d
fct_relevel(f, rev)
#> [1] a b c d
#> Levels: a d c b
# Using 'Inf' allows you to relevel to the end when the number
# of levels is unknown or variable (e.g. vectorised operations)
df <- forcats::gss_cat[, c("rincome", "denom")]
lapply(df, levels)
#> $rincome
#> [1] "No answer" "Don't know" "Refused" "$25000 or more"
#> [5] "$20000 - 24999" "$15000 - 19999" "$10000 - 14999" "$8000 to 9999"
#> [9] "$7000 to 7999" "$6000 to 6999" "$5000 to 5999" "$4000 to 4999"
#> [13] "$3000 to 3999" "$1000 to 2999" "Lt $1000" "Not applicable"
#>
#> $denom
#> [1] "No answer" "Don't know" "No denomination"
#> [4] "Other" "Episcopal" "Presbyterian-dk wh"
#> [7] "Presbyterian, merged" "Other presbyterian" "United pres ch in us"
#> [10] "Presbyterian c in us" "Lutheran-dk which" "Evangelical luth"
#> [13] "Other lutheran" "Wi evan luth synod" "Lutheran-mo synod"
#> [16] "Luth ch in america" "Am lutheran" "Methodist-dk which"
#> [19] "Other methodist" "United methodist" "Afr meth ep zion"
#> [22] "Afr meth episcopal" "Baptist-dk which" "Other baptists"
#> [25] "Southern baptist" "Nat bapt conv usa" "Nat bapt conv of am"
#> [28] "Am bapt ch in usa" "Am baptist asso" "Not applicable"
#>
df2 <- lapply(df, fct_relevel, "Don't know", after = Inf)
lapply(df2, levels)
#> $rincome
#> [1] "No answer" "Refused" "$25000 or more" "$20000 - 24999"
#> [5] "$15000 - 19999" "$10000 - 14999" "$8000 to 9999" "$7000 to 7999"
#> [9] "$6000 to 6999" "$5000 to 5999" "$4000 to 4999" "$3000 to 3999"
#> [13] "$1000 to 2999" "Lt $1000" "Not applicable" "Don't know"
#>
#> $denom
#> [1] "No answer" "No denomination" "Other"
#> [4] "Episcopal" "Presbyterian-dk wh" "Presbyterian, merged"
#> [7] "Other presbyterian" "United pres ch in us" "Presbyterian c in us"
#> [10] "Lutheran-dk which" "Evangelical luth" "Other lutheran"
#> [13] "Wi evan luth synod" "Lutheran-mo synod" "Luth ch in america"
#> [16] "Am lutheran" "Methodist-dk which" "Other methodist"
#> [19] "United methodist" "Afr meth ep zion" "Afr meth episcopal"
#> [22] "Baptist-dk which" "Other baptists" "Southern baptist"
#> [25] "Nat bapt conv usa" "Nat bapt conv of am" "Am bapt ch in usa"
#> [28] "Am baptist asso" "Not applicable" "Don't know"
#>
# You'll get a warning if the levels don't exist
fct_relevel(f, "e")
#> Warning: 1 unknown level in `f`: e
#> [1] a b c d
#> Levels: b c d a