Random Forest Hyperparamter Optimization

[scidam]

The search space in your case is very huge. The number of parameter combinations: 4800 * 3 * 100 * 5 * 5 * 2, but search algorithm checks only 100 (n_iter=100) combinations. So, it is possible that search algorithm chose bad combinations. It would be better, if you reduce the volume of search space, e.g.

n_estimators = [100, 150, 200, 300, 500]
max_depth =[5, 10, 20, 40]