[R] Get Data Table from iml FeatureEffect Object

[Sparks, John]

Hi R-Helpers,

I have recently started working with the iml package (Interpretable Machine Learning)  and its associated material, which I generally find very helpful.

I want to recover some values out of the FeatureEffect Object created by this library, but the form of the object is completely foreign to me.

As a reproducible example:


set.seed(42)​
library("iml")​
library("randomForest")​
data("Boston", package  = "MASS")​
rf = randomForest(medv ~ ., data = Boston, ntree = 50)​
​
X = Boston[which(names(Boston) != "medv")]​
predictor = Predictor$new(rf, data = X, y = Boston$medv)​
imp = FeatureImp$new(predictor, loss = "mae")​
eff = FeatureEffect$new(predictor, feature = "rm") ​
eff


Interpretation method:  FeatureEffect
features: rm[numerical]
grid size: 20

Analysed predictor:
Prediction task: unknown


Analysed data:
Sampling from data.frame with 506 rows and 13 columns.

Head of results:
       .ale .type    rm
1 -2.150574   ale 3.561
2 -2.610528   ale 5.304
3 -2.338677   ale 5.593
4 -2.265673   ale 5.709
5 -2.142912   ale 5.837
6 -2.085899   ale 5.885

How can I refer to and get ahold of the table of 6 records above?

I tried str(eff) and class(eff), but I am not familiar with the structure of the object(s).

Would someone please tell me how to get inside the eff object, or point me to a reference as to what the class or structure of the object is?

Thanks.
--John Sparks

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