Sebastian Sauer saves the levels:
The summary table does not show the level
TRUE, as it is not occuring in the data. This can be problematic: If the data is unknown before summarizing and you would expect that both/all levels (TRUE, FALSE) occur. Just imagine that a subsequent function will count the levelTRUEand the levelFALSE. If one level is missing, your system may brake down.
Click through for a solution, where, even if your dataset is missing a particular level (value of a categorical variable), you will still see it in the final output. That way, if you train a model on this data and the new level shows up in your test dataset or in the wild, it won’t cause an error.