In my classification problem, some of the features(~5) among 85 features have mostly null values (>90%). How do I handle these values? Do I,
1) Ignore these columns/features altogether
2) Try and impute these values, if so how?
3) Any other method?
I am starting with random forests and I am a newbie to this method, does random forest handle null values by itself? How can I implement this? how does random forest do this? Where can I learn about this - any references would be much welcome.
Thanks in advance.