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compact

Reduce size of multiresponse regression model

Since R2024b

    Description

    compactMdl = compact(Mdl) returns a compact model (compactMdl), the compact version of the trained multiresponse regression model Mdl. That is, compactMdl does not contain the training data, whereas Mdl contains the training data in its X, Y, and W properties. You can use either model to compute the loss or predict on new data.

    example

    Examples

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    Reduce the size of a full multiresponse regression model by removing the training data from the model. You can use a compact model to improve memory efficiency.

    Load the carbig data set, which contains measurements of cars made in the 1970s and early 1980s. Create a table containing the predictor variables Displacement, Horsepower, and so on, as well as the response variables Acceleration and MPG. Display the first eight rows of the table.

    load carbig
    cars = table(Displacement,Horsepower,Model_Year, ...
        Origin,Weight,Acceleration,MPG);
    head(cars)
        Displacement    Horsepower    Model_Year    Origin     Weight    Acceleration    MPG
        ____________    __________    __________    _______    ______    ____________    ___
    
            307            130            70        USA         3504           12        18 
            350            165            70        USA         3693         11.5        15 
            318            150            70        USA         3436           11        18 
            304            150            70        USA         3433           12        16 
            302            140            70        USA         3449         10.5        17 
            429            198            70        USA         4341           10        15 
            454            220            70        USA         4354            9        14 
            440            215            70        USA         4312          8.5        14 
    

    Categorize the cars based on whether they were made in the USA.

    cars.Origin = categorical(cellstr(cars.Origin));
    cars.Origin = mergecats(cars.Origin,["France","Japan",...
        "Germany","Sweden","Italy","England"],"NotUSA");

    Remove observations with missing values.

    cars = rmmissing(cars);

    Train a multiresponse regression model by passing the cars data to the fitrchains function. Use regression chains composed of regression SVM models with standardized numeric predictors.

    Mdl = fitrchains(cars,["Acceleration","MPG"], ...
        Learner=templateSVM(Standardize=true))
    Mdl = 
      RegressionChainEnsemble
               PredictorNames: {'Displacement'  'Horsepower'  'Model_Year'  'Origin'  'Weight'}
                 ResponseName: ["Acceleration"    "MPG"]
        CategoricalPredictors: 4
            ResponseTransform: 'none'
              NumObservations: 392
    
    
    

    Mdl is a trained RegressionChainEnsemble model object. The model contains information about the training data set, such as the training data properties X and Y.

    Reduce the size of the model by using the compact object function.

    compactMdl = compact(Mdl)
    compactMdl = 
      CompactRegressionChainEnsemble
               PredictorNames: {'Displacement'  'Horsepower'  'Model_Year'  'Origin'  'Weight'}
                 ResponseName: ["Acceleration"    "MPG"]
        CategoricalPredictors: 4
            ResponseTransform: 'none'
    
    
    

    compactMdl is a CompactRegressionChainEnsemble model object. compactMdl contains fewer properties than the full model Mdl.

    Display the amount of memory used by each model.

    whos("Mdl","compactMdl")
      Name            Size             Bytes  Class                                                    Attributes
    
      Mdl             1x1             125951  RegressionChainEnsemble                                            
      compactMdl      1x1              95825  classreg.learning.regr.CompactRegressionChainEnsemble              
    

    The full model is larger than the compact model.

    Input Arguments

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    Multiresponse regression model, specified as a RegressionChainEnsemble object.

    Output Arguments

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    Compact multiresponse regression model, returned as a CompactRegressionChainEnsemble object.

    Version History

    Introduced in R2024b