% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/to_factor.R
\name{to_factor}
\alias{to_factor}
\alias{to_factor.numeric}
\alias{to_factor.data.frame}
\title{Convert data to factors}
\usage{
to_factor(x, ...)

\method{to_factor}{numeric}(x, labels_to_levels = TRUE, verbose = TRUE, ...)

\method{to_factor}{data.frame}(
  x,
  select = NULL,
  exclude = NULL,
  ignore_case = FALSE,
  append = FALSE,
  regex = FALSE,
  verbose = TRUE,
  ...
)
}
\arguments{
\item{x}{A data frame or vector.}

\item{...}{Arguments passed to or from other methods.}

\item{labels_to_levels}{Logical, if \code{TRUE}, value labels are used as factor
levels after \code{x} was converted to factor. Else, factor levels are based on
the values of \code{x} (i.e. as if using \code{as.factor()}).}

\item{verbose}{Toggle warnings.}

\item{select}{Variables that will be included when performing the required
tasks. Can be either
\itemize{
\item a variable specified as a literal variable name (e.g., \code{column_name}),
\item a string with the variable name (e.g., \code{"column_name"}), a character
vector of variable names (e.g., \code{c("col1", "col2", "col3")}), or a
character vector of variable names including ranges specified via \code{:}
(e.g., \code{c("col1:col3", "col5")}),
\item for some functions, like \code{data_select()} or \code{data_rename()}, \code{select} can
be a named character vector. In this case, the names are used to rename
the columns in the output data frame. See 'Details' in the related
functions to see where this option applies.
\item a formula with variable names (e.g., \code{~column_1 + column_2}),
\item a vector of positive integers, giving the positions counting from the left
(e.g. \code{1} or \code{c(1, 3, 5)}),
\item a vector of negative integers, giving the positions counting from the
right (e.g., \code{-1} or \code{-1:-3}),
\item one of the following select-helpers: \code{starts_with()}, \code{ends_with()},
\code{contains()}, a range using \code{:}, or \code{regex()}. \code{starts_with()},
\code{ends_with()}, and  \code{contains()} accept several patterns, e.g
\code{starts_with("Sep", "Petal")}. \code{regex()} can be used to define regular
expression patterns.
\item a function testing for logical conditions, e.g. \code{is.numeric()} (or
\code{is.numeric}), or any user-defined function that selects the variables
for which the function returns \code{TRUE} (like: \code{foo <- function(x) mean(x) > 3}),
\item ranges specified via literal variable names, select-helpers (except
\code{regex()}) and (user-defined) functions can be negated, i.e. return
non-matching elements, when prefixed with a \code{-}, e.g. \code{-ends_with()},
\code{-is.numeric} or \code{-(Sepal.Width:Petal.Length)}. \strong{Note:} Negation means
that matches are \emph{excluded}, and thus, the \code{exclude} argument can be
used alternatively. For instance, \code{select=-ends_with("Length")} (with
\code{-}) is equivalent to \code{exclude=ends_with("Length")} (no \code{-}). In case
negation should not work as expected, use the \code{exclude} argument instead.
}

If \code{NULL}, selects all columns. Patterns that found no matches are silently
ignored, e.g. \code{extract_column_names(iris, select = c("Species", "Test"))}
will just return \code{"Species"}.}

\item{exclude}{See \code{select}, however, column names matched by the pattern
from \code{exclude} will be excluded instead of selected. If \code{NULL} (the default),
excludes no columns.}

\item{ignore_case}{Logical, if \code{TRUE} and when one of the select-helpers or
a regular expression is used in \code{select}, ignores lower/upper case in the
search pattern when matching against variable names.}

\item{append}{Logical or string. If \code{TRUE}, recoded or converted variables
get new column names and are appended (column bind) to \code{x}, thus returning
both the original and the recoded variables. The new columns get a suffix,
based on the calling function: \code{"_r"} for recode functions, \code{"_n"} for
\code{to_numeric()}, \code{"_f"} for \code{to_factor()}, or \code{"_s"} for
\code{slide()}. If \code{append=FALSE}, original variables in \code{x} will be
overwritten by their recoded versions. If a character value, recoded
variables are appended with new column names (using the defined suffix) to
the original data frame.}

\item{regex}{Logical, if \code{TRUE}, the search pattern from \code{select} will be
treated as regular expression. When \code{regex = TRUE}, select \emph{must} be a
character string (or a variable containing a character string) and is not
allowed to be one of the supported select-helpers or a character vector
of length > 1. \code{regex = TRUE} is comparable to using one of the two
select-helpers, \code{select = contains()} or \code{select = regex()}, however,
since the select-helpers may not work when called from inside other
functions (see 'Details'), this argument may be used as workaround.}
}
\value{
A factor, or a data frame of factors.
}
\description{
Convert data to factors
}
\details{
Convert variables or data into factors. If the data is labelled, value labels
will be used as factor levels. The counterpart to convert variables into
numeric is \code{to_numeric()}.
}
\note{
Factors are ignored and returned as is. If you want to use value labels
as levels for factors, use \code{\link[=labels_to_levels]{labels_to_levels()}} instead.
}
\section{Selection of variables - the \code{select} argument}{

For most functions that have a \code{select} argument (including this function),
the complete input data frame is returned, even when \code{select} only selects
a range of variables. That is, the function is only applied to those variables
that have a match in \code{select}, while all other variables remain unchanged.
In other words: for this function, \code{select} will not omit any non-included
variables, so that the returned data frame will include all variables
from the input data frame.
}

\examples{
str(to_factor(iris))

# use labels as levels
data(efc)
str(efc$c172code)
head(to_factor(efc$c172code))
}