How to set a class_weight Dictionary for Random Forest?
If you're just doing multiclass classification, you should specify the weights as a single dictionary, e.g. {0: 1.0, 1: 1.5, 2: 3.2} for a three-class problem. (Or use the convenience modes &quot;balanced&quot; or &quot;balanced_subsample&quot;).
The list of dictionaries is used for multilabel classification (where each row can have multiple true labels).  In that case, each dictionary is for one of the outputs, the keys being the classes for that output and values the weights.