Converts a sequence of ComboBox features into a vector keeping the top K occurrences of each feature, along with an extra column per feature indicating how many values were not in the top K.
How many values to keep in the vector
Min times a value must occur to be retained in pivot
If true, ignores capitalization and punctuations when grouping categories
keep an extra column that indicated if feature was null
Other ComboBox features to include in pivot
The vectorized features