Description Format Construction Input and Output Channels State Parameters Internals Methods See Also Examples
Collapses factors of type factor
, ordered
: Collapses the rarest factors in the
training samples, until target_level_count
levels remain. Levels that have prevalence above no_collapse_above_prevalence
are retained, however. For factor
variables, these are collapsed to the next larger level, for ordered
variables,
rare variables are collapsed to the neighbouring class, whichever has fewer samples.
Levels not seen during training are not touched during prediction; Therefore it is useful to combine this with the
PipeOpFixFactors
.
R6Class
object inheriting from PipeOpTaskPreprocSimple
/PipeOpTaskPreproc
/PipeOp
.
1  PipeOpCollapseFactors$new(id = "collapsefactors", param_vals = list())

id
:: character(1)
Identifier of resulting object, default "collapsefactors"
.
param_vals
:: named list
List of hyperparameter settings, overwriting the hyperparameter settings that would otherwise be set during construction. Default list()
.
Input and output channels are inherited from PipeOpTaskPreproc
.
The output is the input Task
with rare affected factor
and ordered
feature levels collapsed.
The $state
is a named list
with the $state
elements inherited from PipeOpTaskPreproc
, as well as:
collapse_map
:: named list
of named list
of character
List of factor level maps. For each factor, collapse_map
contains a named list
that indicates what levels
of the input task get mapped to what levels of the output task. If collapse_map
has an entry feat_1
with
an entry a = c("x", "y")
, it means that levels "x"
and "y"
get collapsed to level "a"
in feature "feat_1"
.
The parameters are the parameters inherited from PipeOpTaskPreproc
, as well as:
no_collapse_above_prevalence
:: numeric(1)
Fraction of samples below which factor levels get collapsed. Default is 1, which causes all levels
to be collapsed until target_level_count
remain.
target_level_count
:: integer(1)
Number of levels to retain. Default is 2.
Makes use of the fact that levels(fact_var) = list(target1 = c("source1", "source2"), target2 = "source2")
causes
renaming of level "source1"
and "source2"
both to "target1"
, and also "source2"
to "target2"
.
Only methods inherited from PipeOpTaskPreprocSimple
/PipeOpTaskPreproc
/PipeOp
.
https://mlr3book.mlrorg.com/listpipeops.html
Other PipeOps:
PipeOpEnsemble
,
PipeOpImpute
,
PipeOpTargetTrafo
,
PipeOpTaskPreprocSimple
,
PipeOpTaskPreproc
,
PipeOp
,
mlr_pipeops_boxcox
,
mlr_pipeops_branch
,
mlr_pipeops_chunk
,
mlr_pipeops_classbalancing
,
mlr_pipeops_classifavg
,
mlr_pipeops_classweights
,
mlr_pipeops_colapply
,
mlr_pipeops_colroles
,
mlr_pipeops_copy
,
mlr_pipeops_datefeatures
,
mlr_pipeops_encodeimpact
,
mlr_pipeops_encodelmer
,
mlr_pipeops_encode
,
mlr_pipeops_featureunion
,
mlr_pipeops_filter
,
mlr_pipeops_fixfactors
,
mlr_pipeops_histbin
,
mlr_pipeops_ica
,
mlr_pipeops_imputeconstant
,
mlr_pipeops_imputehist
,
mlr_pipeops_imputelearner
,
mlr_pipeops_imputemean
,
mlr_pipeops_imputemedian
,
mlr_pipeops_imputemode
,
mlr_pipeops_imputeoor
,
mlr_pipeops_imputesample
,
mlr_pipeops_kernelpca
,
mlr_pipeops_learner
,
mlr_pipeops_missind
,
mlr_pipeops_modelmatrix
,
mlr_pipeops_multiplicityexply
,
mlr_pipeops_multiplicityimply
,
mlr_pipeops_mutate
,
mlr_pipeops_nmf
,
mlr_pipeops_nop
,
mlr_pipeops_ovrsplit
,
mlr_pipeops_ovrunite
,
mlr_pipeops_pca
,
mlr_pipeops_proxy
,
mlr_pipeops_quantilebin
,
mlr_pipeops_randomprojection
,
mlr_pipeops_randomresponse
,
mlr_pipeops_regravg
,
mlr_pipeops_removeconstants
,
mlr_pipeops_renamecolumns
,
mlr_pipeops_replicate
,
mlr_pipeops_scalemaxabs
,
mlr_pipeops_scalerange
,
mlr_pipeops_scale
,
mlr_pipeops_select
,
mlr_pipeops_smote
,
mlr_pipeops_spatialsign
,
mlr_pipeops_subsample
,
mlr_pipeops_targetinvert
,
mlr_pipeops_targetmutate
,
mlr_pipeops_targettrafoscalerange
,
mlr_pipeops_textvectorizer
,
mlr_pipeops_threshold
,
mlr_pipeops_tunethreshold
,
mlr_pipeops_unbranch
,
mlr_pipeops_updatetarget
,
mlr_pipeops_vtreat
,
mlr_pipeops_yeojohnson
,
mlr_pipeops
1  library("mlr3")

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