DALEX is designed to work with various black-box models like tree ensembles, linear models, neural networks etc. Unfortunately R packages that create such models are very inconsistent. Different tools use different interfaces to train, validate and use models. One of those tools, which is one of the most popular one is the mlr package. We would like to present dedicated explain function for it.
object - a model to be explained
data.frame or matrix - data which will be used to calculate the explanations. If not provided, then it will be extracted from the model. Data should be passed without a target column (this shall be provided as the y argument). NOTE: If the target variable is present in the data, some of the functionalities may not work properly.
numeric vector with outputs/scores. If provided, then it shall have the same size as data
numeric vector with sampling weights. By default it's NULL. If provided, then it shall have the same length as data
function that takes two arguments: model and new data and returns a numeric vector with predictions. By default it is yhat.
Character or numeric containing either column name or column number in the model prediction object of the class that should be considered as positive (i.e. the class that is associated with probability 1). If NULL, the second column of the output will be taken for binary classification. For a multiclass classification setting, that parameter cause switch to binary classification mode with one vs others probabilities.
function that takes four arguments: model, data, target vector y and predict function (optionally). It should return a numeric vector with model residuals for given data. If not provided, response residuals (\(y-\hat{y}\)) are calculated. By default it is residual_function_default.
other parameters
character - the name of the model. By default it's extracted from the 'class' attribute of the model
logical. If TRUE (default) then diagnostic messages will be printed
logical. If TRUE (default) then predicted_values and residual are calculated when explainer is created.
This will happen also if verbose is TRUE. Set both verbose and precalculate to FALSE to omit calculations.
logical. If TRUE (default) then WARNINGS, ERRORS and NOTES are colorized. Will work only in the R console. Now by default it is FALSE while knitting and TRUE otherwise.
a named list (package, version, type) containing information about model. If NULL, DALEX will seek for information on it's own.
type of a model, either classification or regression. If not specified then type will be extracted from model_info.
explainer object (explain) ready to work with DALEX
library("DALEXtra")
titanic_test <- read.csv(system.file("extdata", "titanic_test.csv", package = "DALEXtra"))
titanic_train <- read.csv(system.file("extdata", "titanic_train.csv", package = "DALEXtra"))
library("mlr")
task <- mlr::makeClassifTask(
id = "R",
data = titanic_train,
target = "survived"
)
learner <- mlr::makeLearner(
"classif.gbm",
par.vals = list(
distribution = "bernoulli",
n.trees = 500,
interaction.depth = 4,
n.minobsinnode = 12,
shrinkage = 0.001,
bag.fraction = 0.5,
train.fraction = 1
),
predict.type = "prob"
)
gbm <- mlr::train(learner, task)
explain_mlr(gbm, titanic_test[,1:17], titanic_test[,18])
#> Preparation of a new explainer is initiated
#> -> model label : WrappedModel ( default )
#> -> data : 524 rows 17 cols
#> -> target variable : 524 values
#> -> predict function : yhat.WrappedModel will be used ( default )
#> -> predicted values : No value for predict function target column. ( default )
#> -> model_info : package mlr , ver. 2.19.0 , task classification ( default )
#> -> predicted values : numerical, min = 0.4355746 , mean = 0.6675312 , max = 0.7298497
#> -> residual function : difference between y and yhat ( default )
#> -> residuals : numerical, min = -0.7298497 , mean = -0.3564625 , max = 0.5644254
#> A new explainer has been created!
#> Model label: WrappedModel
#> Model class: WrappedModel
#> Data head :
#> gender.female gender.male age class.1st class.2nd class.3rd class.deck.crew
#> 1 1 0 16 0 0 1 0
#> 2 0 1 25 0 0 1 0
#> class.engineering.crew class.restaurant.staff class.victualling.crew
#> 1 0 0 0
#> 2 0 0 0
#> embarked.Belfast embarked.Cherbourg embarked.Queenstown embarked.Southampton
#> 1 0 0 0 1
#> 2 0 0 0 1
#> fare sibsp parch
#> 1 7.13 0 0
#> 2 7.13 0 0