Classification Conditional Random Forest Learner

A random forest based on conditional inference trees (ctree). Calls partykit::cforest() from partykit.

Dictionary

This Learner can be instantiated via the dictionary mlr_learners or with the associated sugar function lrn():

mlr_learners$get("classif.cforest")
lrn("classif.cforest")

Meta Information

• Task type: “classif”

• Predict Types: “response”, “prob”

• Feature Types: “integer”, “numeric”, “factor”, “ordered”

• Required Packages: mlr3, mlr3extralearners, partykit, sandwich, coin

Parameters

Id	Type	Default	Levels	Range
ntree	integer	500		\([1, \infty)\)
replace	logical	FALSE	TRUE, FALSE	-
fraction	numeric	0.632		\([0, 1]\)
mtry	integer	-		\([0, \infty)\)
mtryratio	numeric	-		\([0, 1]\)
applyfun	untyped	-		-
cores	integer	NULL		\((-\infty, \infty)\)
trace	logical	FALSE	TRUE, FALSE	-
offset	untyped	-		-
cluster	untyped	-		-
scores	untyped	-		-
teststat	character	quadratic	quadratic, maximum	-
splitstat	character	quadratic	quadratic, maximum	-
splittest	logical	FALSE	TRUE, FALSE	-
testtype	character	Univariate	Bonferroni, MonteCarlo, Univariate, Teststatistic	-
nmax	untyped	-		-
pargs	untyped	-		-
alpha	numeric	0.05		\([0, 1]\)
mincriterion	numeric	0		\([0, 1]\)
logmincriterion	numeric	0		\((-\infty, \infty)\)
minsplit	integer	20		\([1, \infty)\)
minbucket	integer	7		\([1, \infty)\)
minprob	numeric	0.01		\([0, 1]\)
stump	logical	FALSE	TRUE, FALSE	-
lookahead	logical	FALSE	TRUE, FALSE	-
MIA	logical	FALSE	TRUE, FALSE	-
nresample	integer	9999		\([1, \infty)\)
tol	numeric	1.490116e-08		\([0, \infty)\)
maxsurrogate	integer	0		\([0, \infty)\)
numsurrogate	logical	FALSE	TRUE, FALSE	-
maxdepth	integer	Inf		\([0, \infty)\)
multiway	logical	FALSE	TRUE, FALSE	-
splittry	integer	2		\([0, \infty)\)
intersplit	logical	FALSE	TRUE, FALSE	-
majority	logical	FALSE	TRUE, FALSE	-
caseweights	logical	TRUE	TRUE, FALSE	-
saveinfo	logical	FALSE	TRUE, FALSE	-
update	logical	FALSE	TRUE, FALSE	-
splitflavour	character	ctree	ctree, exhaustive	-
maxvar	integer	-		\([1, \infty)\)
OOB	logical	FALSE	TRUE, FALSE	-
simplify	logical	TRUE	TRUE, FALSE	-
scale	logical	TRUE	TRUE, FALSE	-
nperm	integer	1		\([0, \infty)\)
risk	character	loglik	loglik, misclassification	-
conditional	logical	FALSE	TRUE, FALSE	-
threshold	numeric	0.2		\((-\infty, \infty)\)

Custom mlr3 parameters

• mtry:

  • This hyperparameter can alternatively be set via the added hyperparameter mtryratio as mtry = max(ceiling(mtryratio * n_features), 1). Note that mtry and mtryratio are mutually exclusive.

References

Hothorn T, Zeileis A (2015). “partykit: A Modular Toolkit for Recursive Partytioning in R.” Journal of Machine Learning Research, 16(118), 3905-3909. http://jmlr.org/papers/v16/hothorn15a.html.

Hothorn T, Hornik K, Zeileis A (2006). “Unbiased Recursive Partitioning: A Conditional Inference Framework.” Journal of Computational and Graphical Statistics, 15(3), 651--674. doi:10.1198/106186006x133933 , https://doi.org/10.1198/106186006x133933.

See also

• Dictionary of Learners: mlr3::mlr_learners.

• as.data.table(mlr_learners) for a table of available Learners in the running session (depending on the loaded packages).

• Chapter in the mlr3book: https://mlr3book.mlr-org.com/basics.html#learners

• mlr3learners for a selection of recommended learners.

• mlr3cluster for unsupervised clustering learners.

• mlr3pipelines to combine learners with pre- and postprocessing steps.

• mlr3tuning for tuning of hyperparameters, mlr3tuningspaces for established default tuning spaces.

Author

sumny

Super classes

mlr3::Learner -> mlr3::LearnerClassif -> LearnerClassifCForest

Methods

Public methods

• LearnerClassifCForest$new()

• LearnerClassifCForest$oob_error()

• LearnerClassifCForest$clone()

Inherited methods

• mlr3::Learner$base_learner()
• mlr3::Learner$format()
• mlr3::Learner$help()
• mlr3::Learner$predict()
• mlr3::Learner$predict_newdata()
• mlr3::Learner$print()
• mlr3::Learner$reset()
• mlr3::Learner$train()

---

Method new()

Creates a new instance of this R6 class.

Usage

LearnerClassifCForest$new()

---

Method oob_error()

The importance scores are calculated using partykit::varimp().

The out-of-bag error, calculated using the OOB predictions from partykit.

Usage

LearnerClassifCForest$oob_error()

Returns

numeric(1).

---

Method clone()

The objects of this class are cloneable with this method.

Usage

LearnerClassifCForest$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

learner = mlr3::lrn("classif.cforest")
print(learner)
#> <LearnerClassifCForest:classif.cforest>: Conditional Random Forest
#> * Model: -
#> * Parameters: teststat=quadratic, testtype=Univariate, mincriterion=0,
#>   saveinfo=FALSE
#> * Packages: mlr3, mlr3extralearners, partykit, sandwich, coin
#> * Predict Types:  [response], prob
#> * Feature Types: integer, numeric, factor, ordered
#> * Properties: multiclass, oob_error, twoclass, weights

# available parameters:
learner$param_set$ids()
#>  [1] "ntree"           "replace"         "fraction"        "mtry"           
#>  [5] "mtryratio"       "applyfun"        "cores"           "trace"          
#>  [9] "offset"          "cluster"         "scores"          "teststat"       
#> [13] "splitstat"       "splittest"       "testtype"        "nmax"           
#> [17] "pargs"           "alpha"           "mincriterion"    "logmincriterion"
#> [21] "minsplit"        "minbucket"       "minprob"         "stump"          
#> [25] "lookahead"       "MIA"             "nresample"       "tol"            
#> [29] "maxsurrogate"    "numsurrogate"    "maxdepth"        "multiway"       
#> [33] "splittry"        "intersplit"      "majority"        "caseweights"    
#> [37] "saveinfo"        "update"          "splitflavour"    "maxvar"         
#> [41] "OOB"             "simplify"        "scale"           "nperm"          
#> [45] "risk"            "conditional"     "threshold"