Candidate 0/1 encodings of a column, where the meaning is unambiguous

A predictor can only be an exact copy of a binary outcome if it carries the same two-valued information, so this answers a narrow question: can this column be read as 0/1 without guessing. Numeric columns holding only 0 and 1, logicals, and any column with exactly two observed values qualify. Everything else does not, which is what keeps an arbitrary string from being coerced into an outcome.

Usage

mm_binary_forms(values)

Arguments

values

A candidate predictor column.

Value

A list of encodings, each a list of code (0/1 integer with NA preserved) and label (how it was read). Empty when the column cannot be read as binary without guessing.

Details

Two encodings are returned for a two-valued column, one per choice of which value marks the event, because the labels are arbitrary and a comparison that trusted them would miss a copy whose levels happen to read backwards.