featureExtractors.py 文件源码

def getFeatures(self, state, action):
    # extract the grid of food and wall locations and get the ghost locations
    food = state.getFood()
    walls = state.getWalls()
    ghosts = state.getGhostPositions()

    features = util.Counter()

    features["bias"] = 1.0

    # compute the location of pacman after he takes the action
    x, y = state.getPacmanPosition()
    dx, dy = Actions.directionToVector(action)
    next_x, next_y = int(x + dx), int(y + dy)

    # count the number of ghosts 1-step away
    features["#-of-ghosts-1-step-away"] = sum((next_x, next_y) in Actions.getLegalNeighbors(g, walls) for g in ghosts)

    # if there is no danger of ghosts then add the food feature
    if not features["#-of-ghosts-1-step-away"] and food[next_x][next_y]:
      features["eats-food"] = 1.0

    dist = closestFood((next_x, next_y), food, walls)
    if dist is not None:
      # make the distance a number less than one otherwise the update
      # will diverge wildly
      features["closest-food"] = float(dist) / (walls.width * walls.height) 
    features.divideAll(10.0)
    return features