Remove dependency on gym.utils

flatland/action_plan/__init__.py

@@ -0,0 +1,3 @@
+from warnings import warn
+
+warn('The action_plan is deprecated', DeprecationWarning, stacklevel=2)

flatland/contrib/__init__.py

@@ -0,0 +1,3 @@
+from warnings import warn
+
+warn('The contrib is deprecated', DeprecationWarning, stacklevel=2)

flatland/envs/rail_env.py

@@ -5,7 +5,7 @@
 from typing import List, Optional, Dict, Tuple
 
 import numpy as np
-from gym.utils import seeding
+from flatland.utils import seeding
 
 from flatland.core.env import Environment
 from flatland.core.env_observation_builder import ObservationBuilder

flatland/utils/seeding.py

@@ -0,0 +1,91 @@
+import hashlib
+import os
+import struct
+
+import numpy as np
+
+def np_random(seed=None):
+    if seed is not None and not (isinstance(seed, int) and 0 <= seed):
+        raise Exception('Seed must be a non-negative integer or omitted, not {}'.format(seed))
+
+    seed = create_seed(seed)
+
+    rng = np.random.RandomState()
+    rng.seed(_int_list_from_bigint(hash_seed(seed)))
+    return rng, seed
+
+
+def hash_seed(seed=None, max_bytes=8):
+    """Any given evaluation is likely to have many PRNG's active at
+    once. (Most commonly, because the environment is running in
+    multiple processes.) There's literature indicating that having
+    linear correlations between seeds of multiple PRNG's can correlate
+    the outputs:
+
+    http://blogs.unity3d.com/2015/01/07/a-primer-on-repeatable-random-numbers/
+    http://stackoverflow.com/questions/1554958/how-different-do-random-seeds-need-to-be
+    http://dl.acm.org/citation.cfm?id=1276928
+
+    Thus, for sanity we hash the seeds before using them. (This scheme
+    is likely not crypto-strength, but it should be good enough to get
+    rid of simple correlations.)
+
+    Args:
+        seed (Optional[int]): None seeds from an operating system specific randomness source.
+        max_bytes: Maximum number of bytes to use in the hashed seed.
+    """
+    if seed is None:
+        seed = create_seed(max_bytes=max_bytes)
+    hash = hashlib.sha512(str(seed).encode('utf8')).digest()
+    return _bigint_from_bytes(hash[:max_bytes])
+
+
+def create_seed(a=None, max_bytes=8):
+    """Create a strong random seed. Otherwise, Python 2 would seed using
+    the system time, which might be non-robust especially in the
+    presence of concurrency.
+
+    Args:
+        a (Optional[int, str]): None seeds from an operating system specific randomness source.
+        max_bytes: Maximum number of bytes to use in the seed.
+    """
+    # Adapted from https://svn.python.org/projects/python/tags/r32/Lib/random.py
+    if a is None:
+        a = _bigint_from_bytes(os.urandom(max_bytes))
+    elif isinstance(a, str):
+        a = a.encode('utf8')
+        a += hashlib.sha512(a).digest()
+        a = _bigint_from_bytes(a[:max_bytes])
+    elif isinstance(a, int):
+        a = a % 2 ** (8 * max_bytes)
+    else:
+        raise Exception('Invalid type for seed: {} ({})'.format(type(a), a))
+
+    return a
+
+
+# TODO: don't hardcode sizeof_int here
+def _bigint_from_bytes(bytes):
+    sizeof_int = 4
+    padding = sizeof_int - len(bytes) % sizeof_int
+    bytes += b'\0' * padding
+    int_count = int(len(bytes) / sizeof_int)
+    unpacked = struct.unpack("{}I".format(int_count), bytes)
+    accum = 0
+    for i, val in enumerate(unpacked):
+        accum += 2 ** (sizeof_int * 8 * i) * val
+    return accum
+
+
+def _int_list_from_bigint(bigint):
+    # Special case 0
+    if bigint < 0:
+        raise Exception('Seed must be non-negative, not {}'.format(bigint))
+    elif bigint == 0:
+        return [0]
+
+    ints = []
+    while bigint > 0:
+        bigint, mod = divmod(bigint, 2 ** 32)
+        ints.append(mod)
+    return ints

pyproject.toml

@@ -25,7 +25,6 @@ dependencies = [
     "crowdai_api",
     "dataclasses",
     "graphviz",
-    "gym==0.14.0",
     "importlib_resources<2.0.0",
     "ipycanvas",
     "ipyevents",