Thank you for the post, I just want to add that there is some machine learning approaches that automatically estimate the mark objects. Shameless self-promotion

Thank you for the post, I just want to add that there is some machine learning approaches that automatically estimate the mark objects. Shameless self-promotion: https://github.com/GHamrouni/Recommender https://github.com/GHamrouni/Recommender it is a C library for product recommendations/suggestions using collaborative filtering (CF).