Clean up typing

src/probnum/random_variables/_dirac.py

@@ -5,12 +5,13 @@
 import numpy as np
 
 from probnum import utils as _utils
-from probnum._lib.argtypes import (
+from probnum.typing import (
+    ShapeType,
+    # Argument Types
     ArrayLikeGetitemArgType,
     RandomStateArgType,
     ShapeArgType,
 )
-from probnum.typing import ShapeType
 
 from . import _random_variable
 

src/probnum/random_variables/_normal.py

@@ -6,14 +6,15 @@
 import scipy.stats
 
 from probnum import utils as _utils
-from probnum._lib.argtypes import (
+from probnum.linalg import linops
+from probnum.typing import (
+    ShapeType,
+    # Argument Types
     ArrayLikeGetitemArgType,
     FloatArgType,
     RandomStateArgType,
     ShapeArgType,
 )
-from probnum.linalg import linops
-from probnum.typing import ShapeType
 
 from . import _random_variable
 

src/probnum/random_variables/_random_variable.py

@@ -10,13 +10,15 @@
 import numpy as np
 
 from probnum import utils as _utils
-from probnum._lib.argtypes import (
+from probnum.typing import (
+    RandomStateType,
+    ShapeType,
+    # Argument Types
     DTypeArgType,
     FloatArgType,
     RandomStateArgType,
     ShapeArgType,
 )
-from probnum.typing import RandomStateType, ShapeType
 
 try:
     # functools.cached_property is only available in Python >=3.8

src/probnum/typing.py

@@ -1,7 +1,36 @@
-from typing import Tuple, Union
+import numbers
+from typing import Iterable, Tuple, Union
 
 import numpy as np
 
+########################################################################################
+# API Types
+########################################################################################
+
 ShapeType = Tuple[int, ...]
 
 RandomStateType = Union[np.random.RandomState, np.random.Generator]
+
+########################################################################################
+# Argument Types
+########################################################################################
+
+IntArgType = Union[int, numbers.Integral, np.integer]
+FloatArgType = Union[float, numbers.Real, np.floating]
+
+ShapeArgType = Union[IntArgType, Iterable[IntArgType]]
+DTypeArgType = Union[np.dtype, str]
+
+ScalarArgType = Union[int, float, complex, numbers.Number, np.float_]
+
+ArrayLikeGetitemArgType = Union[
+    int,
+    slice,
+    np.ndarray,
+    np.newaxis,
+    None,
+    type(Ellipsis),
+    Tuple[Union[int, slice, np.ndarray, np.newaxis, None, type(Ellipsis)], ...],
+]
+
+RandomStateArgType = Union[None, int, np.random.RandomState, np.random.Generator]

src/probnum/utils/__init__.py

@@ -2,7 +2,6 @@
 from .arrayutils import *
 from .fctutils import *
 from .randomutils import *
-from .scalarutils import *
 
 # Public classes and functions. Order is reflected in documentation.
 __all__ = [

src/probnum/utils/argutils.py

@@ -3,8 +3,20 @@
 import numpy as np
 import scipy._lib._util
 
-from probnum.typing import ShapeType, RandomStateType
-from probnum._lib.argtypes import ShapeArgType, RandomStateArgType
+from probnum.typing import (
+    DTypeArgType,
+    RandomStateArgType,
+    RandomStateType,
+    ScalarArgType,
+    ShapeArgType,
+    ShapeType,
+)
+
+__all__ = ["as_shape", "as_random_state", "as_numpy_scalar"]
+
+
+def as_random_state(x: RandomStateArgType) -> RandomStateType:
+    return scipy._lib._util.check_random_state(x)
 
 
 def as_shape(x: ShapeArgType) -> ShapeType:
@@ -26,5 +38,11 @@ def as_shape(x: ShapeArgType) -> ShapeType:
         return tuple(int(item) for item in x)
 
 
-def as_random_state(x: RandomStateArgType) -> RandomStateType:
-    return scipy._lib._util.check_random_state(x)
+def as_numpy_scalar(x: ScalarArgType, dtype: DTypeArgType = None) -> np.generic:
+    is_scalar = np.isscalar(x)
+    is_scalar_array = isinstance(x, np.ndarray) and x.ndim == 0
+
+    if not (is_scalar or is_scalar_array):
+        raise ValueError("The given input is not a scalar.")
+
+    return np.asarray(x, dtype=dtype)[()]