ENH: Updates to numpy.array_api (#19937)

* Add __index__ to array_api and update __int__, __bool__, and __float__

The spec specifies that they should only work on arrays with corresponding
dtypes. __index__ is new in the spec since the initial PR, and works
identically to np.array.__index__.

* Add the to_device method to the array_api

This method is new since #18585. It does nothing in NumPy since NumPy does not
support non-CPU devices.

* Update transpose methods in the array_api

transpose() was renamed to matrix_transpose() and now operates on stacks of
matrices. A function to permute dimensions will be added once it is finalized
in the spec. The attribute mT was added and the T attribute was updated to
only operate on 2-dimensional arrays as per the spec.

* Restrict input dtypes in the array API statistical functions

* Add the dtype parameter to the array API sum() and prod()

* Add the function permute_dims() to the array_api namespace

permute_dims() is the replacement for transpose(), which was split into
permute_dims() and matrix_transpose().

* Add tril and triu to the array API namespace

* Fix the array_api Array.__repr__ to indent the array properly

* Make the Device type in the array_api just accept the string "cpu"

1 files changed, 24 insertions, 6 deletions

diff --git a/numpy/array_api/tests/test_array_object.py b/numpy/array_api/tests/test_array_object.py
index 088e09b9f..7959f92b4 100644
--- a/numpy/array_api/tests/test_array_object.py
+++ b/numpy/array_api/tests/test_array_object.py
@@ -1,3 +1,5 @@
+import operator
+
 from numpy.testing import assert_raises
 import numpy as np
 
@@ -255,15 +257,31 @@ def test_operators():
 
 
 def test_python_scalar_construtors():
-    a = asarray(False)
-    b = asarray(0)
-    c = asarray(0.0)
+    b = asarray(False)
+    i = asarray(0)
+    f = asarray(0.0)
 
-    assert bool(a) == bool(b) == bool(c) == False
-    assert int(a) == int(b) == int(c) == 0
-    assert float(a) == float(b) == float(c) == 0.0
+    assert bool(b) == False
+    assert int(i) == 0
+    assert float(f) == 0.0
+    assert operator.index(i) == 0
 
     # bool/int/float should only be allowed on 0-D arrays.
     assert_raises(TypeError, lambda: bool(asarray([False])))
     assert_raises(TypeError, lambda: int(asarray([0])))
     assert_raises(TypeError, lambda: float(asarray([0.0])))
+    assert_raises(TypeError, lambda: operator.index(asarray([0])))
+
+    # bool/int/float should only be allowed on arrays of the corresponding
+    # dtype
+    assert_raises(ValueError, lambda: bool(i))
+    assert_raises(ValueError, lambda: bool(f))
+
+    assert_raises(ValueError, lambda: int(b))
+    assert_raises(ValueError, lambda: int(f))
+
+    assert_raises(ValueError, lambda: float(b))
+    assert_raises(ValueError, lambda: float(i))
+
+    assert_raises(TypeError, lambda: operator.index(b))
+    assert_raises(TypeError, lambda: operator.index(f))