fctcount

fctcount is a function from the R package forcats, part of the tidyverse ecosystem. It is used to determine the number of levels in a factor. Factors in R are categorical variables that have a fixed set of levels, which can be ordered or unordered. The fctcount function returns an integer representing the count of distinct levels in the input factor.

The function signature is fctcount(x, levels_only = FALSE). The first argument, x, must be a factor or a character vector that will be coerced to a factor. The optional argument levels_only, when set to TRUE, causes the function to return only the number of levels without any additional attributes; otherwise, it returns an integer vector that retains the factor's attributes.

When applied to a factor with levels “a”, “b”, “c”, fctcount returns 3. If the factor has duplicated levels, these are not counted multiple times; only unique levels are considered. For character vectors, trailing and leading white space is preserved in the level naming, so “foo” and “foo ” are considered distinct levels.

fctcount is particularly useful in data manipulation pipelines. For example, when using dplyr to group by a categorical variable, one might compute the number of factor levels in each group to diagnose missing categories or to perform conditional logic based on level count.

The function is implemented in pure R and has no external dependencies beyond forcats. It adheres to the tidyverse style guidelines, accepting both standard and pipe operators. Since its introduction in forcats version 0.5.0, fctcount has become a common utility in workflows involving categorical data analysis.

Overall, fctcount provides a quick, reliable way to quantify the categorical breadth of a variable, which is often a first step in exploratory data analysis or data cleaning tasks.