Cross validation with decision trees

franky99franky99 Member Posts: 2 Newbie
Hello everyone, when using for example a k fold cross validation strategy with 10 folds with decision trees, 10 trees are built.
When outputting the results for cross validation, only one tree/model is shown. How is that tree calculated exactly?

Best Answer

  • BalazsBaranyBalazsBarany Administrator, Moderator, Employee, RapidMiner Certified Analyst, RapidMiner Certified Expert Posts: 860 Unicorn
    Solution Accepted
    Hi!

    When the model output of the Cross Validation operator is connected, it calculates a last (11th) model from all the data. So your tree was built from all data and applying the training phase on them.

    If you're interested in the ten other trees, you can set a breakpoint inside the cross validation and take a look at them. With some automation (e. g. Generate Macro incrementing the loop number) you can also store the validation models in the repository.

    Regards,
    Balázs

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