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kfoldPredict

Predict responses for observations in cross-validated regression model

    Description

    example

    yfit = kfoldPredict(CVMdl) returns responses predicted by the cross-validated regression model CVMdl. For every fold, kfoldPredict predicts the responses for validation-fold observations using a model trained on training-fold observations. CVMdl.X and CVMdl.Y contain both sets of observations.

    yfit = kfoldPredict(CVMdl,'IncludeInteractions',includeInteractions) specifies whether to include interaction terms in computations. This syntax applies only to generalized additive models.

    Examples

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    When you create a cross-validated regression model, you can compute the mean squared error (MSE) by using the kfoldLoss object function. Alternatively, you can predict responses for validation-fold observations using kfoldPredict and compute the MSE manually.

    Load the carsmall data set. Specify the predictor data X and the response data Y.

    load carsmall
    X = [Cylinders Displacement Horsepower Weight];
    Y = MPG;

    Train a cross-validated regression tree model. By default, the software implements 10-fold cross-validation.

    rng('default') % For reproducibility
    CVMdl = fitrtree(X,Y,'CrossVal','on');

    Compute the 10-fold cross-validation MSE by using kfoldLoss.

    L = kfoldLoss(CVMdl)
    L = 29.4963
    

    Predict the responses yfit by using the cross-validated regression model. Compute the mean squared error between yfit and the true responses CVMdl.Y. The computed MSE matches the loss value returned by kfoldLoss.

    yfit = kfoldPredict(CVMdl);
    mse = mean((yfit - CVMdl.Y).^2)
    mse = 29.4963
    

    Input Arguments

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    Cross-validated partitioned regression model, specified as a RegressionPartitionedModel, RegressionPartitionedEnsemble, RegressionPartitionedGAM, or RegressionPartitionedSVM object. You can create the in two ways:

    • Pass a trained regression model listed in the following table to its crossval object function.

    • Train a regression model using a function listed in the following table and specify one of the cross-validation name-value arguments for the function.

    Flag to include interaction terms of the model, specified as true or false. This argument is valid only for a generalized additive model (GAM). That is, you can specify this argument only when CVMdl is RegressionPartitionedGAM.

    The default value is true if the models in CVMdl (CVMdl.Trained) contain interaction terms. The value must be false if the models do not contain interaction terms.

    Data Types: logical

    Output Arguments

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    Predicted responses, returned as an n-by-1 numeric vector, where n is the number of observations. (n is size(CVMdl.X,1) when observations are in rows.) Each entry of yfit corresponds to the predicted response for the corresponding row of CVMdl.X.

    If you use a holdout validation technique to create CVMdl (that is, if CVMdl.KFold is 1), then yfit has NaN values for training-fold observations.

    Introduced in R2011a