ftl.py

from .randmax import randmax
import numpy as np
from .base_mab import BaseMAB

class FTL(BaseMAB):
    """follow the leader (a.k.a. greedy strategy)
    
    Parameters
    ----------
    nbArms :int,
        Number of arms of bandit
    """
    def __init__(self,nbArms):
        self.nbArms = nbArms
        self.clear()

    def clear(self):
        self.nbDraws = np.zeros(self.nbArms)
        self.cumRewards = np.zeros(self.nbArms)
    
    def chooseArmToPlay(self):
        if (min(self.nbDraws)==0):
            return randmax(-self.nbDraws)
        else:
            return randmax(self.cumRewards/self.nbDraws)

    def receiveReward(self,arm,reward):
        self.cumRewards[arm] = self.cumRewards[arm]+reward
        self.nbDraws[arm] = self.nbDraws[arm] +1