tiles_sutton.py

"""
Allowing myself to use http://incompleteideas.net/tiles/tiles3.py-remove
because the link is in the book page 246 and i've already implemented
tile coding in chapter 9.
"""

from math import floor
from itertools import zip_longest

basehash = hash


class IHT:
  "Structure to handle collisions"
  def __init__(self, sizeval):
    self.size = sizeval
    self.overfullCount = 0
    self.dictionary = {}

  def __str__(self):
    "Prepares a string for printing whenever this object is printed"
    return "Collision table:" + \
           " size:" + str(self.size) + \
           " overfullCount:" + str(self.overfullCount) + \
           " dictionary:" + str(len(self.dictionary)) + " items"

  def count(self):
    return len(self.dictionary)

  def fullp(self):
    return len(self.dictionary) >= self.size

  def getindex(self, obj, readonly=False):
    d = self.dictionary
    if obj in d:
      return d[obj]
    elif readonly:
      return None
    size = self.size
    count = self.count()
    if count >= size:
      if self.overfullCount == 0:
        print('IHT full, starting to allow collisions')
      self.overfullCount += 1
      return basehash(obj) % self.size
    else:
      d[obj] = count
      return count


def hashcoords(coordinates, m, readonly=False):
  if type(m) == IHT:
    return m.getindex(tuple(coordinates), readonly)
  if type(m) == int:
    return basehash(tuple(coordinates)) % m
  if m is None:
    return coordinates


def tiles(ihtORsize, numtilings, floats, ints=[], readonly=False):
  """returns num-tilings tile indices corresponding to the floats and ints"""
  qfloats = [floor(f*numtilings) for f in floats]
  Tiles = []
  for tiling in range(numtilings):
    tilingX2 = tiling*2
    coords = [tiling]
    b = tiling
    for q in qfloats:
      coords.append((q + b) // numtilings)
      b += tilingX2
    coords.extend(ints)
    Tiles.append(hashcoords(coords, ihtORsize, readonly))
  return Tiles


def tileswrap(ihtORsize, numtilings, floats, wrapwidths, ints=[],
              readonly=False):
  """
  returns num-tilings tile indices corresponding to the floats and ints,
  wrapping some floats
  """
  qfloats = [floor(f*numtilings) for f in floats]
  Tiles = []
  for tiling in range(numtilings):
    tilingX2 = tiling*2
    coords = [tiling]
    b = tiling
    for q, width in zip_longest(qfloats, wrapwidths):
      c = (q + b % numtilings) // numtilings
      coords.append(c % width if width else c)
      b += tilingX2
    coords.extend(ints)
    Tiles.append(hashcoords(coords, ihtORsize, readonly))
  return Tiles