It converts all the variables present in 'data' to character. Criteria conversion is based on
two functions, discretize_get_bins
plus discretize_df
, which will discretize
all the numerical variables based on equal frequency criteria, with the number of bins equal to 'n_bins'.
This only applies for numerical variables which unique valuesare more than 'n_bins' parameter.
After this step, it may happen that variables remain non-character, so these variables will be converting
directly into character.