Fix return hint for EnumerableSpace.get_elements() and simplify imple…

…mentations

In code, the result of `EnumerableSpace.get_elements()` is used for:
- `for a in elements`
- `if a in elements`
- `elements[i]`
- `len(elements)`
- `random.sample(elements, 2)`

So this is actually expected to be `Sequence`.
We fix the annotation and simplify the implementation by removing the
wrapping in numpy.array() as it is not expected and even sometimes
re-wrap in a numpy.array() in the code.

examples/nocycle_grid_goal_mdp.py

@@ -4,7 +4,7 @@
 
 import getopt
 import sys
-from collections.abc import Iterable
+from collections.abc import Sequence
 from enum import IntEnum
 from math import sqrt
 from typing import NamedTuple, Optional
@@ -45,7 +45,7 @@ def __init__(self, state=None, num_cols=0, num_rows=0):
         self.num_cols = num_cols
         self.num_rows = num_rows
 
-    def get_elements(self) -> Iterable[int]:
+    def get_elements(self) -> Sequence[int]:
         if self.state is None:
             return [a for a in MyActions]
         else:

skdecide/builders/domain/scheduling/scheduling_domains.py

@@ -5,7 +5,7 @@
 from __future__ import annotations
 
 import random
-from collections.abc import Iterable
+from collections.abc import Sequence
 from enum import Enum
 from itertools import product
 from typing import Optional
@@ -1219,7 +1219,7 @@ def __init__(self, domain: SchedulingDomain, state: State):
         self.state = state
         self.elements = self._get_elements()
 
-    def _get_elements(self) -> Iterable[T]:
+    def _get_elements(self) -> Sequence[T]:
         choices = [
             SchedulingActionEnum.START,
             SchedulingActionEnum.PAUSE,
@@ -1282,7 +1282,7 @@ def _get_elements(self) -> Iterable[T]:
                 )
         return list_action
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return self.elements
 
     def sample(self) -> T:
@@ -1299,7 +1299,7 @@ def __init__(self, domain: SchedulingDomain, state: State):
         self.state = state
         self.elements = self._get_elements()
 
-    def _get_elements(self) -> Iterable[T]:
+    def _get_elements(self) -> Sequence[T]:
         choices = [
             SchedulingActionEnum.START,
             SchedulingActionEnum.PAUSE,
@@ -1382,7 +1382,7 @@ def _get_elements(self) -> Iterable[T]:
                 )
         return list_action
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return self.elements
 
     def sample(self) -> T:

skdecide/core.py

@@ -117,7 +117,7 @@ def contains(self, x: T) -> bool:
 class EnumerableSpace(Space[T]):
     """A space which elements can be enumerated."""
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         """Get the elements of this space.
 
         # Returns
@@ -132,7 +132,7 @@ def contains(self, x: T) -> bool:
 class EmptySpace(EnumerableSpace[T]):
     """An (enumerable) empty space."""
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return ()
 
 

skdecide/hub/domain/graph_domain/GraphDomain.py

@@ -5,7 +5,7 @@
 from __future__ import annotations
 
 import random
-from collections.abc import Iterable
+from collections.abc import Sequence
 from typing import Optional
 
 import networkx as nx
@@ -44,7 +44,7 @@ def contains(self, x: T) -> bool:
     def __init__(self, l: list[object]):
         self.l = l
 
-    def get_elements(self) -> Iterable[object]:
+    def get_elements(self) -> Sequence[object]:
         return self.l
 
 

skdecide/hub/space/gym/gym.py

@@ -84,13 +84,13 @@ def __init__(self, n, element_class=int):
         super().__init__(gym_space=gym_spaces.Discrete(n))
         self._element_class = element_class
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         """Get the elements of this space.
 
         # Returns
         The elements of this space.
         """
-        return np.array(list(range(self._gym_space.n)), dtype=np.int64)
+        return range(self._gym_space.n)
 
     def to_unwrapped(self, sample_n: Iterable[T]) -> Iterable:
         return (
@@ -118,16 +118,13 @@ def __init__(self, nvec, element_class=np.ndarray):
         super().__init__(gym_space=gym_spaces.MultiDiscrete(nvec))
         self._element_class = element_class
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         """Get the elements of this space.
 
         # Returns
         The elements of this space.
         """
-        return np.array(
-            list(itertools.product(*[list(range(n)) for n in self._gym_space.nvec])),
-            dtype=np.int64,
-        )
+        return tuple(itertools.product(*(range(n) for n in self._gym_space.nvec)))
 
     def to_unwrapped(self, sample_n: Iterable[T]) -> Iterable:
         return (
@@ -155,16 +152,13 @@ def __init__(self, n, element_class=np.ndarray):
         super().__init__(gym_space=gym_spaces.MultiBinary(n))
         self._element_class = element_class
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         """Get the elements of this space.
 
         # Returns
         The elements of this space.
         """
-        return np.array(
-            list(itertools.product(*[(1, 0) for _ in range(self._gym_space.n)])),
-            dtype=np.int8,
-        )
+        return tuple(itertools.product(*((1, 0) for _ in range(self._gym_space.n))))
 
     def to_unwrapped(self, sample_n: Iterable[T]) -> Iterable:
         return (
@@ -311,14 +305,14 @@ def __init__(self, enum_class: EnumMeta) -> None:
         enum_class: The enumeration class for creating the Gym Discrete space (gym.spaces.Discrete) to wrap.
         """
         self._enum_class = enum_class
-        self._list_enum = list(enum_class)
+        self._list_enum = tuple(enum_class)
         gym_space = gym_spaces.Discrete(len(enum_class))
         super().__init__(gym_space)
 
     def contains(self, x: T) -> bool:
         return isinstance(x, self._enum_class)
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return self._list_enum
 
     def sample(self) -> T:
@@ -367,7 +361,7 @@ def __init__(self, elements: Iterable[T]) -> None:
     def contains(self, x: T) -> bool:
         return x in self._elements
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return self._elements
 
     def sample(self) -> T:
@@ -417,7 +411,7 @@ def __init__(self, elements: Iterable[T]) -> None:
     def contains(self, x: T) -> bool:
         return x in self._elements
 
-    def get_elements(self) -> Iterable[T]:
+    def get_elements(self) -> Sequence[T]:
         return self._elements
 
     def sample(self) -> T: