Currently, it is not possible to use mlrMBO for tuning mlr3 and related packages
directly, because of some disagreements between S3 (as used in mlrMBO)
and R6 (used in mlr3). mlr3mbo exists, but it is
not yet as mature and feature-rich as mlrMBO. mlrintermbo
provides the necessary interface to make mlrMBO accessible for mlr3.
To use mlrintermbo, one should NOT load
mlrMBO as a library in the current R session. Instead,
mlrintermbo will run mlrMBO on a different background R
session to keep it sectioned off from the main process. Just load the
tuner (for tuning mlr3 “Learners”) or optimizer (for tuning bbotk
“Objectives”):
library("mlrintermbo")
# Tuning Learners:
library("mlr3tuning")
tuner <- tnr("intermbo")
# Tuning Objectives
library("bbotk")
optimizer <- opt("intermbo")The tuner / optimizer provide an extensive
ParamSet to configure the MBO method, covering practically
everything that can usually be configured with an
MBOControl object. To find out the specific function of
each control parameter, read the mlrMBO
reference entries of functions regarding “mlrMBO Control”.
When installing mlrintermbo, the required
mlrMBO package is not installed automatically. It is
therefore necessary to install mlrMBO manually:
install.packages("mlrMBO")
install.packages("mlrintermbo")Assertion on ‘xdt’ failed
r Error in .__OptimInstance__eval_batch(self = self, private = private, : Assertion on 'xdt' failed: Must have at least 1 rows, but has 0 rows.
This is caused by a bug in the
callr package. The bug is fixed on CRAN, installing the
current versions using
install.packages(c("callr", "processx")) should fix the
issue.
Most other errors
Some errors, for example
Error: Domains[,1] must be less than or equal to Domains[,2]are caused because the surrogate model is failing. (The error above
happens when the objective function is giving constant values, which the
surrogate learner does not handle well). Initialize the tuner with
on.surrogate.error set to "warn" or
"quiet" to ignore errors of the surrogate model. E.g.:
tuner <- tnr("intermbo", on.surrogate.error = "warn") # alternatively "quiet"LGPL-3