Description Details Usage Methods See Also
Parent or superclass of all {contextual}
Bandit
subclasses.
In {contextual}
, Bandits
are responsible for the generation of (either
synthetic or offline) contexts and rewards.
On initialisation, a Bandit
subclass has to define the number of arms self$k
and the number of contextual feature dimensions self$d
.
For each t = 1, ..., T a Bandit
then generates a list
containing
current context in d x k
dimensional matrix context$X
,
the number of arms in context$k
and the number of features in context$d
.
Note: in context-free scenario's, context$X
can be omitted.
On receiving the index of a Policy
-chosen arm through action$choice
,
Bandit
is expected to return a named list
containing at least reward$reward
and, where computable, reward$optimal
.
1 |
new()
generates and instantializes a new Bandit
instance.
get_context(t)
argument:
t
: integer, time step t
.
returns a named list
containing the current d x k
dimensional matrix context$X
,
the number of arms context$k
and the number of features context$d
.
get_reward(t, context, action)
arguments:
t
: integer, time step t
.
context
: list, containing the current context$X
(d x k context matrix),
context$k
(number of arms) and context$d
(number of context features)
(as set by bandit
).
action
: list, containing action$choice
(as set by policy
).
returns a named list
containing reward$reward
and, where computable,
reward$optimal
(used by "oracle" policies and to calculate regret).
post_initialization()
Called after class and seed initialisation, but before the start of the simulation.
Set random values that remain available throughout the life of a Bandit
here.
generate_bandit_data()
Called after class and seed initialisation, but before the start of a simulation.
Pregenerate contexts
and rewards
here.
Core contextual classes: Bandit
, Policy
, Simulator
,
Agent
, History
, Plot
Bandit subclass examples: BasicBernoulliBandit
, ContextualLogitBandit
,
OfflineReplayEvaluatorBandit
Policy subclass examples: EpsilonGreedyPolicy
, ContextualLinTSPolicy
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