parse_factor: Parse factors

In readr: Read Rectangular Text Data

Parse factors

Description

parse_factor() is similar to factor(), but generates a warning if levels have been specified and some elements of x are not found in those levels.

Usage

parse_factor(
  x,
  levels = NULL,
  ordered = FALSE,
  na = c("", "NA"),
  locale = default_locale(),
  include_na = TRUE,
  trim_ws = TRUE
)

col_factor(levels = NULL, ordered = FALSE, include_na = FALSE)

Arguments

x	Character vector of values to parse.
levels	Character vector of the allowed levels. When levels = NULL (the default), levels are discovered from the unique values of x, in the order in which they appear in x.
ordered	Is it an ordered factor?
na	Character vector of strings to interpret as missing values. Set this option to character() to indicate no missing values.
locale	The locale controls defaults that vary from place to place. The default locale is US-centric (like R), but you can use locale() to create your own locale that controls things like the default time zone, encoding, decimal mark, big mark, and day/month names.
include_na	If TRUE and x contains at least one NA, then NA is included in the levels of the constructed factor.
trim_ws	Should leading and trailing whitespace (ASCII spaces and tabs) be trimmed from each field before parsing it?

See Also

Other parsers: col_skip(), cols_condense(), cols(), parse_datetime(), parse_guess(), parse_logical(), parse_number(), parse_vector()

Examples

# discover the levels from the data
parse_factor(c("a", "b"))
parse_factor(c("a", "b", "-99"))
parse_factor(c("a", "b", "-99"), na = c("", "NA", "-99"))
parse_factor(c("a", "b", "-99"), na = c("", "NA", "-99"), include_na = FALSE)

# provide the levels explicitly
parse_factor(c("a", "b"), levels = letters[1:5])

x <- c("cat", "dog", "caw")
animals <- c("cat", "dog", "cow")

# base::factor() silently converts elements that do not match any levels to
# NA
factor(x, levels = animals)

# parse_factor() generates same factor as base::factor() but throws a warning
# and reports problems
parse_factor(x, levels = animals)

readr documentation built on May 29, 2024, 2:37 a.m.