cpoCache: Caches the Result of CPO Transformations

Description Usage Arguments Value General CPO info Calling a CPOConstructor See Also

View source: R/CPO_meta.R


This is a CPOConstructor to be used to create a CPO. It is called like any R function and returns the created CPO.

Given a CPO to wrap, this caches an intermediate result (in fact, the retrafo object) whenever the CPO is applied to a Task or data.frame. This can reduce computation time when the same CPO is often applied to the same data, e.g. in a resampling or tuning evaluation.

The hyperparameters of the CPO are not exported, since in many cases changing the hyperparameters will also change the result and would defeat the point of caching. To switch between different settings of the same CPO, consider using cpoMultiplex.

The cache is kept in an environment; therefore, it does not communicate with other threads or processes when using parallelization at a level before the cache gets filled.

Caching needs the ‘digest’ package to be installed.


cpoCache(cpo = NULLCPO, cache.entries = 1024)



The CPO to wrap. The CPO may only have a single OperatingType. Default is NULLCPO.


Number of entries in the least recently used cache.



General CPO info

This function creates a CPO object, which can be applied to Tasks, data.frames, link{Learner}s and other CPO objects using the %>>% operator.

The parameters of this object can be changed after creation using the function setHyperPars. The other hyper-parameter manipulating functins, getHyperPars and getParamSet similarly work as one expects.

If the “id” parameter is given, the hyperparameters will have this id as aprefix; this will, however, not change the parameters of the creator function.

Calling a CPOConstructor

CPO constructor functions are called with optional values of parameters, and additional “special” optional values. The special optional values are the id parameter, and the affect.* parameters. The affect.* parameters enable the user to control which subset of a given dataset is affected. If no affect.* parameters are given, all data features are affected by default.

See Also

Other CPOs: cpoApplyFunRegrTarget, cpoApplyFun, cpoAsNumeric, cpoCbind, cpoCollapseFact, cpoDropConstants, cpoDummyEncode, cpoFilterAnova, cpoFilterCarscore, cpoFilterChiSquared, cpoFilterFeatures, cpoFilterGainRatio, cpoFilterInformationGain, cpoFilterKruskal, cpoFilterLinearCorrelation, cpoFilterOneR, cpoFilterPermutationImportance, cpoFilterRankCorrelation, cpoFilterRelief, cpoFilterRfCImportance, cpoFilterRfImportance, cpoFilterRfSRCImportance, cpoFilterRfSRCMinDepth, cpoFilterSymmetricalUncertainty, cpoFilterUnivariate, cpoFilterVariance, cpoFixFactors, cpoIca, cpoImpactEncodeClassif, cpoImpactEncodeRegr, cpoImputeConstant, cpoImputeHist, cpoImputeLearner, cpoImputeMax, cpoImputeMean, cpoImputeMedian, cpoImputeMin, cpoImputeMode, cpoImputeNormal, cpoImputeUniform, cpoImpute, cpoLogTrafoRegr, cpoMakeCols, cpoMissingIndicators, cpoModelMatrix, cpoOversample, cpoPca, cpoProbEncode, cpoQuantileBinNumerics, cpoRegrResiduals, cpoResponseFromSE, cpoSample, cpoScaleMaxAbs, cpoScaleRange, cpoScale, cpoSelect, cpoSmote, cpoSpatialSign, cpoTransformParams, cpoWrap, makeCPOCase, makeCPOMultiplex

mlr-org/mlrCPO documentation built on Feb. 4, 2019, 12:16 p.m.