LiblineaR Classification Learner

L2 regularized support vector classification. Calls LiblineaR::LiblineaR() from LiblineaR.

Details

Type of SVC depends on type argument:

• 0 – L2-regularized logistic regression (primal)

• 1 - L2-regularized L2-loss support vector classification (dual)

• 3 - L2-regularized L1-loss support vector classification (dual)

• 2 – L2-regularized L2-loss support vector classification (primal)

• 4 – Support vector classification by Crammer and Singer

• 5 - L1-regularized L2-loss support vector classification

• 6 - L1-regularized logistic regression

• 7 - L2-regularized logistic regression (dual)

If number of records > number of features, type = 2 is faster than type = 1 (Hsu et al. 2003).

Note that probabilistic predictions are only available for types 0, 6, and 7. The default epsilon value depends on the type parameter, see LiblineaR::LiblineaR().

Dictionary

This Learner can be instantiated via lrn():

lrn("classif.liblinear")

Meta Information

• Task type: “classif”

• Predict Types: “response”, “prob”

• Feature Types: “numeric”

• Required Packages: mlr3, mlr3extralearners, LiblineaR

Parameters

Id	Type	Default	Levels	Range
type	integer	0		\([0, 7]\)
cost	numeric	1		\([0, \infty)\)
epsilon	numeric	-		\([0, \infty)\)
bias	numeric	1		\((-\infty, \infty)\)
cross	integer	0		\([0, \infty)\)
verbose	logical	FALSE	TRUE, FALSE	-
wi	untyped	NULL		-
findC	logical	FALSE	TRUE, FALSE	-
useInitC	logical	TRUE	TRUE, FALSE	-

References

Fan, Rong-En, Chang, Kai-Wei, Hsieh, Cho-Jui, Wang, Xiang-Rui, Lin, Chih-Jen (2008). “LIBLINEAR: A library for large linear classification.” the Journal of machine Learning research, 9, 1871–1874.

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/chapters/chapter2/data_and_basic_modeling.html#sec-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

be-marc

Super classes

mlr3::Learner -> mlr3::LearnerClassif -> LearnerClassifLiblineaR

Methods

Public methods

• LearnerClassifLiblineaR$new()

• LearnerClassifLiblineaR$clone()

Inherited methods

• mlr3::Learner$base_learner()
• mlr3::Learner$configure()
• mlr3::Learner$encapsulate()
• mlr3::Learner$format()
• mlr3::Learner$help()
• mlr3::Learner$predict()
• mlr3::Learner$predict_newdata()
• mlr3::Learner$print()
• mlr3::Learner$reset()
• mlr3::Learner$selected_features()
• mlr3::Learner$train()
• mlr3::LearnerClassif$predict_newdata_fast()

---

LearnerClassifLiblineaR$new()

Creates a new instance of this R6 class.

Usage

LearnerClassifLiblineaR$new()

---

LearnerClassifLiblineaR$clone()

The objects of this class are cloneable with this method.

Usage

LearnerClassifLiblineaR$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

# Define the Learner
learner = lrn("classif.liblinear")
print(learner)
#> 
#> ── <LearnerClassifLiblineaR> (classif.liblinear): Support Vector Machine ───────
#> • Model: -
#> • Parameters: list()
#> • Packages: mlr3, mlr3extralearners, and LiblineaR
#> • Predict Types: [response] and prob
#> • Feature Types: numeric
#> • Encapsulation: none (fallback: -)
#> • Properties: multiclass and twoclass
#> • Other settings: use_weights = 'error', predict_raw = 'FALSE'

# Define a Task
task = tsk("sonar")

# Create train and test set
ids = partition(task)

# Train the learner on the training ids
learner$train(task, row_ids = ids$train)

print(learner$model)
#> $TypeDetail
#> [1] "L2-regularized logistic regression primal (L2R_LR)"
#> 
#> $Type
#> [1] 0
#> 
#> $W
#>              V1       V10        V11       V12        V13        V14      V15
#> [1,] -0.2554701 -0.513421 -0.9856333 -1.020212 -0.6548117 0.08137784 0.723414
#>            V16       V17        V18        V19         V2        V20        V21
#> [1,] 0.8734893 0.7424871 0.07357369 -0.1402192 -0.2129134 -0.4399208 -0.5908435
#>             V22        V23        V24       V25      V26       V27        V28
#> [1,] -0.7326877 -0.4628399 -0.2117532 0.1290413 0.194853 0.4347117 0.07867701
#>               V29         V3         V30       V31        V32       V33
#> [1,] -0.009056155 -0.1443291 -0.08522314 0.6031817 0.06735788 0.2116136
#>            V34      V35       V36      V37         V38        V39         V4
#> [1,] 0.6697625 0.381772 0.8761647 1.087279 -0.05560357 -0.4404807 -0.5097513
#>            V40         V41        V42       V43       V44       V45        V46
#> [1,] 0.2203695 -0.04479037 -0.5843105 -1.309223 -1.153215 -1.205715 -0.9630928
#>             V47        V48        V49         V5         V50         V51
#> [1,] -0.4045224 -0.4335707 -0.3423262 -0.5825174 -0.04883567 -0.08339089
#>              V52         V53         V54        V55         V56        V57
#> [1,] -0.08081238 -0.03948982 -0.03374749 0.02953892 -0.01424665 0.02757073
#>              V58         V59         V6         V60        V7          V8
#> [1,] -0.02698713 -0.03876812 -0.2127401 -0.03214824 0.1249896 -0.05689248
#>              V9      Bias
#> [1,] -0.6310529 0.8600388
#> 
#> $Bias
#> [1] 1
#> 
#> $ClassNames
#> [1] R M
#> Levels: M R
#> 
#> $NbClass
#> [1] 2
#> 
#> attr(,"class")
#> [1] "LiblineaR"


# Make predictions for the test rows
predictions = learner$predict(task, row_ids = ids$test)

# Score the predictions
predictions$score()
#> classif.ce 
#>  0.3043478