Change discrete dtype to np.int64 (#141)

gymnasium/spaces/discrete.py

@@ -1,14 +1,14 @@
 """Implementation of a space consisting of finitely many elements."""
 from __future__ import annotations
 
-from typing import Any, Iterable, Mapping
+from typing import Any, Iterable, Mapping, Sequence
 
 import numpy as np
 
 from gymnasium.spaces.space import MaskNDArray, Space
 
 
-class Discrete(Space[int]):
+class Discrete(Space[np.int64]):
     r"""A space consisting of finitely many elements.
 
     This class represents a finite subset of integers, more specifically a set of the form :math:`\{ a, a+1, \dots, a+n-1 \}`.
@@ -21,9 +21,9 @@ class Discrete(Space[int]):
 
     def __init__(
         self,
-        n: int,
+        n: int | np.integer[Any],
         seed: int | np.random.Generator | None = None,
-        start: int = 0,
+        start: int | np.integer[Any] = 0,
     ):
         r"""Constructor of :class:`Discrete` space.
 
@@ -34,11 +34,16 @@ class Discrete(Space[int]):
             seed: Optionally, you can use this argument to seed the RNG that is used to sample from the ``Dict`` space.
             start (int): The smallest element of this space.
         """
-        assert isinstance(n, (int, np.integer))
+        assert np.issubdtype(
+            type(n), np.integer
+        ), f"Expects `n` to be an integer, actual dtype: {type(n)}"
         assert n > 0, "n (counts) have to be positive"
-        assert isinstance(start, (int, np.integer))
-        self.n = int(n)
-        self.start = int(start)
+        assert np.issubdtype(
+            type(start), np.integer
+        ), f"Expects `start` to be an integer, actual type: {type(start)}"
+
+        self.n = np.int64(n)
+        self.start = np.int64(start)
         super().__init__((), np.int64, seed)
 
     @property
@@ -74,26 +79,26 @@ class Discrete(Space[int]):
                 np.logical_or(mask == 0, valid_action_mask)
             ), f"All values of a mask should be 0 or 1, actual values: {mask}"
             if np.any(valid_action_mask):
-                return int(
-                    self.start + self.np_random.choice(np.where(valid_action_mask)[0])
+                return self.start + self.np_random.choice(
+                    np.where(valid_action_mask)[0]
                 )
             else:
                 return self.start
 
-        return int(self.start + self.np_random.integers(self.n))
+        return self.start + self.np_random.integers(self.n)
 
     def contains(self, x: Any) -> bool:
         """Return boolean specifying if x is a valid member of this space."""
         if isinstance(x, int):
-            as_int = x
+            as_int64 = np.int64(x)
         elif isinstance(x, (np.generic, np.ndarray)) and (
             np.issubdtype(x.dtype, np.integer) and x.shape == ()
         ):
-            as_int = int(x)
+            as_int64 = np.int64(x)
         else:
             return False
 
-        return self.start <= as_int < self.start + self.n
+        return bool(self.start <= as_int64 < self.start + self.n)
 
     def __repr__(self) -> str:
         """Gives a string representation of this space."""
@@ -123,6 +128,14 @@ class Discrete(Space[int]):
         # Allow for loading of legacy states.
         # See https://github.com/openai/gym/pull/2470
         if "start" not in state:
-            state["start"] = 0
+            state["start"] = np.int64(0)
 
         super().__setstate__(state)
+
+    def to_jsonable(self, sample_n: Sequence[np.int64]) -> list[int]:
+        """Converts a list of samples to a list of ints."""
+        return [int(x) for x in sample_n]
+
+    def from_jsonable(self, sample_n: list[int]) -> list[np.int64]:
+        """Converts a list of json samples to a list of np.int64."""
+        return [np.int64(x) for x in sample_n]

gymnasium/spaces/utils.py

@@ -160,7 +160,7 @@ def _flatten_box_multibinary(space: Box | MultiBinary, x: NDArray[Any]) -> NDArr
 
 
 @flatten.register(Discrete)
-def _flatten_discrete(space: Discrete, x: int) -> NDArray[np.int64]:
+def _flatten_discrete(space: Discrete, x: np.int64) -> NDArray[np.int64]:
     onehot = np.zeros(space.n, dtype=space.dtype)
     onehot[x - space.start] = 1
     return onehot
@@ -268,14 +268,14 @@ def _unflatten_box_multibinary(
 
 
 @unflatten.register(Discrete)
-def _unflatten_discrete(space: Discrete, x: NDArray[np.int64]) -> int:
-    return int(space.start + np.nonzero(x)[0][0])
+def _unflatten_discrete(space: Discrete, x: NDArray[np.int64]) -> np.int64:
+    return space.start + np.nonzero(x)[0][0]
 
 
 @unflatten.register(MultiDiscrete)
 def _unflatten_multidiscrete(
-    space: MultiDiscrete, x: NDArray[np.int32]
-) -> NDArray[np.int32]:
+    space: MultiDiscrete, x: NDArray[np.integer[Any]]
+) -> NDArray[np.integer[Any]]:
     offsets = np.zeros((space.nvec.size + 1,), dtype=space.dtype)
     offsets[1:] = np.cumsum(space.nvec.flatten())