Handle imbalanced data

[florianschwanz]

Balance input data by undersampling majority classes. Follow these tutorials

• https://towardsdatascience.com/methods-for-dealing-with-imbalanced-data-5b761be45a18
• https://towardsdatascience.com/heres-what-i-ve-learnt-about-sklearn-resample-ab735ae1abc4