crossvaldata function

Computes k-fold cross validation for rminer models.

crossvaldata(x, data, theta.fit, theta.predict, ngroup = 10, 
             mode = "stratified", seed = NULL, model, task, feature = "none",
             ...)

Arguments

• x: See fit for details.
• data: See fit for details.
• theta.fit: fitting function
• theta.predict: prediction function
• ngroup: number of folds
• mode: Possibilities are: "stratified", "random" or "order" (see holdout for details).
• seed: if NULL then no seed is used and the current R randomness is assumed; else a fixed seed is adopted to generate local random sample sequences, returning always the same result for the same seed (local means that it does not affect the state of other random number generations called after this function, see holdout example).
• model: See fit for details.
• task: See fit for details.
• feature: See fit for details.
• ...: Additional parameters sent to theta.fit or theta.predic (e.g. search)

Details

Standard k-fold cross-validation adopted for rminer models. By default, for classification tasks ("class" or "prob") a stratified sampling is used (the class distributions are identical for each fold), unless mode is set to random or order

(see holdout for details).

Note

A better control (e.g. use of several Runs) is achieved using the simpler mining function.

Returns

Returns a list with:

• $cv.fit -- all predictions (factor if task="class", matrix if task="prob" or numeric if task="reg");
• $model -- vector list with the model for each fold.
• $mpar -- vector list with the mpar for each fold;
• $attributes -- the selected attributes for each fold if a feature selection algorithm was adopted;
• $ngroup -- the number of folds;
• $leave.out -- the computed size for each fold (=nrow(data)/ngroup);
• $groups -- vector list with the indexes of each group;
• $call -- the call of this function;

References

Check the crossval function.

Author(s)

This function was adapted by Paulo Cortez from the crossval function of the bootstrap library (S original by R. Tibshirani and R port by F. Leisch).

See Also

holdout, fit, mining and predict.fit.

Examples

### dontrun is used when the execution of the example requires some computational effort.
## Not run:

 data(iris)
 # 3-fold cross validation using fit and predict
 # the control argument is sent to rpart function 
 # rpart.control() is from the rpart package
 M=crossvaldata(Species~.,iris,fit,predict,ngroup=3,seed=12345,model="rpart",
                task="prob", control = rpart::rpart.control(cp=0.05))
 print("cross validation object:")
 print(M)
 C=mmetric(iris$Species,M$cv.fit,metric="CONF")
 print("confusion matrix:")
 print(C)
## End(Not run)