How to construct a regression tree

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Salad Box 2019-1-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/438801-how-to-construct-a-regression-tree

编辑： Stephen23 2019-1-9

Hi,

As I was trying to understand the matlab example on the documentation page for constructing a regression tree https://uk.mathworks.com/help/stats/regressiontree-class.html, below is the example.

>> load carsmall;
>> whos
  Name                Size            Bytes  Class     Attributes
  Acceleration      100x1               800  double              
  Cylinders         100x1               800  double              
  Displacement      100x1               800  double              
  Horsepower        100x1               800  double              
  MPG               100x1               800  double              
  Mfg               100x13             2600  char                
  Model             100x33             6600  char                
  Model_Year        100x1               800  double              
  Origin            100x7              1400  char                
  Weight            100x1               800  double   
  
  >> tree = fitrtree([Weight, Cylinders],MPG,...
                'categoricalpredictors',2,'MinParentSize',20,...
                'PredictorNames',{'W','C'})
tree = 
  RegressionTree
           PredictorNames: {'W'  'C'}
             ResponseName: 'Y'
    CategoricalPredictors: 2
        ResponseTransform: 'none'
          NumObservations: 94
  Properties, Methods
  
  >> mileage4K = predict(tree,[4000 4; 4000 6; 4000 8])
mileage4K =
   19.2778
   19.2778
   14.3889

I wonder how the mileage is predicted while there is no variable in 'carsmall' named mileage.

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Salad Box 2019-1-9

编辑：Salad Box 2019-1-9

Yes you are right. Someone who constructed 'fitrtree' documentation webpage has comfirmed that the varialbe 'MPG' is the variable 'mileage'. But as someone living in the UK, mileage means the total miles a car has been driven.

Thanks for answering!