# Policies.klUCBloglog_forGLR module¶

The generic kl-UCB policy for one-parameter exponential distributions with restarted round count t_k. By default, it assumes Bernoulli arms. Note: using log(t) + c log(log(t)) for the KL-UCB index of just log(t) - It is designed to be used with the wrapper GLR_UCB. - By default, it assumes Bernoulli arms. - Reference: [Garivier & Cappé - COLT, 2011](https://arxiv.org/pdf/1102.2490.pdf).

Policies.klUCBloglog_forGLR.c = 3

Default value when using $$f(t) = \log(t) + c \log(\log(t))$$, as klUCB_forGLR is inherited from klUCBloglog.

Policies.klUCBloglog_forGLR.TOLERANCE = 0.0001

Default value for the tolerance for computing numerical approximations of the kl-UCB indexes.

class Policies.klUCBloglog_forGLR.klUCBloglog_forGLR(nbArms, tolerance=0.0001, klucb=CPUDispatcher(<function klucbBern>), c=2, lower=0.0, amplitude=1.0)[source]

The generic KL-UCB policy for one-parameter exponential distributions, using a different exploration time step for each arm ($$\log(t_k) + c \log(\log(t_k))$$ instead of $$\log(t) + c \log(\log(t))$$).

• It is designed to be used with the wrapper GLR_UCB.
__init__(nbArms, tolerance=0.0001, klucb=CPUDispatcher(<function klucbBern>), c=2, lower=0.0, amplitude=1.0)[source]

New generic index policy.

• nbArms: the number of arms,

• lower, amplitude: lower value and known amplitude of the rewards.

computeIndex(arm)[source]

Compute the current index, at time t and after $$N_k(t)$$ pulls of arm k:

$\begin{split}\hat{\mu}_k(t) &= \frac{X_k(t)}{N_k(t)}, \\ U_k(t) &= \sup\limits_{q \in [a, b]} \left\{ q : \mathrm{kl}(\hat{\mu}_k(t), q) \leq \frac{\log(t) + c \log(\max(1, \log(t)))}{N_k(t)} \right\},\\ I_k(t) &= U_k(t).\end{split}$

If rewards are in $$[a, b]$$ (default to $$[0, 1]$$) and $$\mathrm{kl}(x, y)$$ is the Kullback-Leibler divergence between two distributions of means x and y (see Arms.kullback), and c is the parameter (default to 1).

computeAllIndex()[source]

Compute the current indexes for all arms, in a vectorized manner.

__module__ = 'Policies.klUCBloglog_forGLR'