<p dir="auto">Very much like OneHotEncoder, but will have a parameter for setting threshold. If a feature value occurs more than the specified threshold, then it will get encoded like OneHotEncoder. Otherwise, feature values occurring fewer than the threshold, they will get encoded into the last bit of the encoded array.</p>
<p dir="auto">The OneHotEncoder should have an option to summarize categories that are not frequent - or we should have another transformer to do that beforehand.<br>
Generally having a maximum number of categories or having a minimum frequency per category would make sense as thresholds. This is similar to what we're doing in CountVectorizer but I think common enough for categorical variables that we should explicitly make it easy to do.</p>