Collapse factor levels into manually defined groups
Combine levels from two or more factors to create a new factor
Reorder factor levels by first appearance, frequency, or numeric order
Lump together factor levels into "other"
Automatically relabel factor levels, collapse as necessary
Reorder factor levels by sorting along another variable
Shift factor levels to left or right, wrapping around at end
forcats: Tools for Working with Categorical Variables (Factors)
A sample of categorical variables from the General Social survey
Low-level functions for manipulating levels