title: Random Forest Regressor using a custom objective/ loss function (Python/ Sklearn)
body: <p>I want to build a Random Forest Regressor to model count data (Poisson distribution). The default 'mse' loss function is not suited to this problem. Is there a way to define a custom loss function and pass it to the random forest regressor in Python (Sklearn, etc..)? </p>
  
  <p>Is there any implementation to fit count data in Python in any packages?</p>