v2fct {str2str}

Character Vector to (Unordered) Factor

Description

v2fct converts a character vector to a (unordered) factor. It goes beyond as.factor by allowing you to specify how you want the levels ordered and whether you want NA treated as a level.

Usage

v2fct(
  v,
  order.lvl = "position",
  decreasing = FALSE,
  na.lvl = FALSE,
  check = TRUE
)

Arguments

v

character vector. If it is not a character vector (e.g., factor, numeric vector), then it is coerced to a character vector within v2fct.

order.lvl

character vector of length 1 specifying how you want to order the levels of the factor. The options are "alphanum", which sorts the levels alphanumerically (with NA last); "position", which sorts the levels by the position the level first appears; "frequency", which sorts the levels by their frequency. If any frequencies are tied, then the ties are sorted alphanumerically (with NA last).

decreasing

logical vector of length 1 specifying whether the ordering of the levels should be decreasing (TRUE) rather than increasing (FALSE).

na.lvl

logical vector of length 1 specifying if NA should be considered a level.

check

logical vector of length 1 specifying whether to check the structure of the input arguments. For example, check whether v is an atomic vector. This argument is available to allow flexibility in whether the user values informative error messages (TRUE) vs. computational efficiency (FALSE).

Details

When order.lvl = "alpanum" the levels are sorted alphabetically if letters or a combination of letters and numbers/numerals are in present in v. If only numbers/numerals are present in v, then levels are sorted numerically.

Value

factor of length = length(x) and names = names(x).

Examples

# no missing values
state_region <- as.character(state.region)
v2fct(state_region, order.lvl = "position") # in position order
v2fct(v = state_region, order.lvl = "frequency",
   decreasing = TRUE) # most frequent to least frequent
v2fct(v = state_region, order.lvl = "alphanum") # in alphanumerical order
v2fct(v = state_region, na.lvl = TRUE) # na.lvl is inert because no NAs in `v`
# with missing values
state_region <- c(NA_character_, as.character(state.region), NA_character_)
v2fct(v = state_region, order.lvl = "position", na.lvl = TRUE)
v2fct(v = state_region, order.lvl = "frequency", decreasing = TRUE, na.lvl = TRUE)
v2fct(v = state_region, order.lvl = "alphanum", na.lvl = TRUE)
identical(x = v2fct(v = state_region, order.lvl = "alphanum"),
   y = as.factor(state_region)) # equal to as.factor()
# numeric vectors
v2fct(v = round(faithful$"eruptions"), order.lvl = "position")
v2fct(v = round(faithful$"eruptions"), order.lvl = "frequency", decreasing = TRUE)
v2fct(v = round(faithful$"eruptions"), order.lvl = "alphanum")
# cnumeric vectors
cnum <- c("100","99","10","9","1","0","100","99","10","9","1","0")
factor(cnum) # not in numerical order
v2fct(v = cnum, order.lvl = "alphanum") # yes in numerical order
# ties on frequency
v2fct(v = rev(npk$"block"), order.lvl = "alphanum") # ties sorted alphanumerically
v2fct(v = rev(npk$"block"), order.lvl = "position") # no possibility of ties