Block usage of nested ifelse() calls

Calling ifelse in nested calls is problematic for two main reasons:

1. It can be hard to read -- mapping the code to the expected output for such code can be a messy task/require a lot of mental bandwidth, especially for code that nests more than once

2. It is inefficient -- ifelse can evaluate all of its arguments at both yes and no (see https://stackoverflow.com/q/16275149); this issue is exacerbated for nested calls

Usage

nested_ifelse_linter()

Details

Users can instead rely on a more readable alternative modeled after SQL CASE WHEN statements, such as data.table::fcase or dplyr::case_when, or use a look-up-and-merge approach (build a mapping table between values and outputs and merge this to the input).

See also

linters for a complete list of linters available in lintr.

Tags

efficiency, readability