compact

Reduce size of multiresponse regression model

Since R2024b

Syntax

compactMdl = compact(Mdl)

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.

Examples

Reduce Size of Multiresponse Regression Model

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

Mdl — Multiresponse regression model

RegressionChainEnsemble object

Multiresponse regression model, specified as a RegressionChainEnsemble object.

Output Arguments

compactMdl — Compact multiresponse regression model

CompactRegressionChainEnsemble object

Compact multiresponse regression model, returned as a CompactRegressionChainEnsemble object.

Version History

Introduced in R2024b