MATLAB: How to retrieve optimal MinLeafSize after automatic hyperparameter optimization for Tree Ensemble (fitrensemble)

baggingboostingensemblefitrensemblerandom forestsregression treesStatistics and Machine Learning Toolbox

Hi. I am running MATLAB's automatic Bayesian optimization for a number of parameters for a Tree Ensemble. 
opts = struct('Kfold',4,'Optimizer','bayesopt');
Mdl = fitrensemble(X,Y,'OptimizeHyperparameters',{'Method','NumLearningCycles','LearnRate','MinLeafSize'},'HyperparameterOptimizationOptions',opts);
I understand that all the optimal parameters are embedded in the resulted object ‘Mdl’, but I was wondering if it’s possible to retrieve and save in a variable the optimal MinLeafSize. Even though I have found the rest optimized parameters: 
Mdl.ModelParameters.Method %Method
Mdl.ModelParameters.NLearn %NumLearningCycles
Mdl.ModelParameters.LearnRate %LearnRate
but, I cannot obtain the MinLeafSize. However, I can see that it is listed among the properties of 'Mdl' under MinLeaf:
Mdl.ModelParameters.LearnerTemplates{1,1}
Anyone knows how to extract this? Thanks.

Best Answer

I ran both a tree and ensemble models optimizing minLeafSize. For a decision tree, MinLeaf is a model parameter, but not for an ensemble. The only way I could find to see the value was by viewing the template.
Mdl.ModelParameters.LearnerTemplates{1,1}
ans = 
Fit template for regression Tree.
        SplitCriterion: []
             MinParent: []
               MinLeaf: 126
             MaxSplits: 10
          NVarToSample: []
           MergeLeaves: 'off'
                 Prune: 'off'
        PruneCriterion: []
               QEToler: []
            NSurrogate: []
                MaxCat: []
                AlgCat: []
    PredictorSelection: []
          UseChisqTest: []
                Stream: []
          Reproducible: []
               Version: 2
                Method: 'Tree'
                  Type: 'regression'
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