add history frame player

tensorpack/RL/history.py

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+# File: history.py
+# Author: Yuxin Wu <ppwwyyxxc@gmail.com>
+
+import numpy as np
+from collections import deque
+from .envbase import ProxyPlayer
+
+__all__ = ['HistoryFramePlayer']
+
+class HistoryFramePlayer(ProxyPlayer):
+    """ Include history frames in state, or use black images"""
+    def __init__(self, player, hist_len):
+        """ :params hist_len: total length of the state, including the current
+            and `hist_len-1` history"""
+        super(HistoryFramePlayer, self).__init__(player)
+        self.history = deque(maxlen=hist_len)
+
+        s = self.player.current_state()
+        self.history.append(s)
+
+    def current_state(self):
+        assert len(self.history) != 0
+        diff_len = self.history.maxlen - len(self.history)
+        if diff_len == 0:
+            return np.concatenate(self.history, axis=2)
+        zeros = [np.zeros_like(self.history[0]) for k in range(diff_len)]
+        for k in self.history:
+            zeros.append(k)
+        return np.concatenate(zeros, axis=2)
+
+    def action(self, act):
+        r, isOver = self.player.action(act)
+        s = self.player.current_state()
+        self.history.append(s)
+
+        if isOver:  # s would be a new episode
+            self.history.clear()
+            self.history.append(s)
+        return (r, isOver)
+
+    def restart_episode(self):
+        super(HistoryFramePlayer, self).restart_episode()
+        self.history.clear()
+        self.history.append(self.player.current_state())
+
+class TimePointHistoryFramePlayer(HistoryFramePlayer):
+    """ Include history from a list of time points in the past"""
+    def __init__(self, player, hists):
+        """ hists: a list of positive integers. 1 means the last frame"""
+        queue_size = max(hists) + 1
+        super(TimePointHistoryFramePlayer, self).__init__(player, queue_size)
+        self.hists = hists
+
+    def current_state(self):
+        # TODO
+        pass