zhengruifeng commented on issue #27337: [SPARK-30545][ML][PYSPARK] Impl 
Extremely Randomized Trees
URL: https://github.com/apache/spark/pull/27337#issuecomment-578405903
 
 
   @huaxingao Good point, you are right. Scikit-Learn does this exactly:
   ```
                       # Draw a random threshold
                       current.threshold = rand_uniform(min_feature_value,
                                                        max_feature_value,
                                                        random_state)
   ```
   
   In Scikit-Learn, both RF and ET use a greedy method to find an exact 
threshold.
   However, in MLLIB, all tree models are built on binned datasets 
(`treePoints`), to keep in line with other tree models and to minimize the 
change, I perfer to randomly draw a split from splits built at the beginning of 
training. Otherwise, I need to completely impl a new exact threshold finding 
method.

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