[BUG] Inconsistent environment seeding

[facebookresearch]

[BUG] Inconsistent environment seeding

[samvelyan]

Hi @jlin816

Thanks for pointing this out and apologies for a late reply.

I see where the issue is. Firstly, MiniHack's seeding is slightly different from that of NLE's. The seeds argument in of a MiniHack environment assumes a list of integers which is used as a training distribution for an agent, e.g. [1, 3, 9, 27]. (Perhaps the documentation should make this clearer)

minihack/minihack/base.py

Lines 175 to 177 in 2054e7f

	seeds (list or None):
	A list of random seeds for sampling episodes. If none, the
	entire level distribution is used. Defaults to None.

Specifically, when a reset function is called, minihack randomly samples one of the seeds, e.g. 27, (they are now stores as self._level_seeds since we treat them as levels of the same environment) and sets it using nle.seed(27, 27, False) like this

minihack/minihack/base.py

Lines 325 to 327 in 2054e7f

	if self._level_seeds is not None:
	seed = random.choice(self._level_seeds)
	self.seed(seed, seed, reseed=False)

I understand this made the seed() function ignored if seeds was originally passed to the environment. Therefore, I added a new parameter in the reset() function of minihack called sample_seed (defaults to True). If True, the reset() function will randomly sample a level from the original list. If False, it will not do so, hence the manually setting the level seed with NLE's seed() function will work as desired.

Here is the PR #68. Please let me know if it works for you.

[samvelyan]

With this new PR, here is how one would use the seeding functionality

import minihack, gym
env = gym.make("MiniHack-KeyRoom-Fixed-S5-v0",
    observation_keys=("pixel", "colors", "chars", "glyphs", "tty_chars"),
    seeds=[1, 3, 9, 27])

For now let's sample random episodes a few times

obs = env.reset()
env.render()
print(env.get_seeds())

This outputs

You are lucky!  Full moon tonight.










                                          |
                                    ----..|
                                    |.....|
                                    |@.(..|
                                    -------






Agent the Footpad              St:13 Dx:17 Co:13 In:13 Wi:13 Ch:9 Chaotic S:0
Dlvl:1 $:0 HP:12(12) Pw:2(2) AC:7 Xp:1/0

(27, 27, False)

or perhaps

You are lucky!  Full moon tonight.








                                       ----
                                       |..|
                                       +..|
                                    ----..|
                                    |.....|
                                    |.(..@|
                                    -------






Agent the Footpad              St:14 Dx:18 Co:13 In:9 Wi:12 Ch:9 Chaotic S:0
Dlvl:1 $:0 HP:12(12) Pw:2(2) AC:7 Xp:1/0

(3, 3, False)

Now when we manually set the seed and use sample_seed=False, we will get the exact level we want

env.seed(42, 42, False)
obs = env.reset(sample_seed=False)
env.render()
print(env.get_seeds())

will result in the following.

You are lucky!  Full moon tonight.








                                       ----
                                       |..|
                                       +(.|
                                    ----..|
                                    |.....|
                                    |...@.|
                                    -------






Agent the Footpad              St:18/02 Dx:18 Co:13 In:8 Wi:9 Ch:7 Chaotic S:0
Dlvl:1 $:0 HP:12(12) Pw:2(2) AC:7 Xp:1/0

(42, 42, False)