Implement np.asarray()

docs/source/reference/numpysupported.rst

@@ -255,6 +255,7 @@ The following top-level functions are supported:
 * :func:`numpy.argsort` (``kind`` key word argument supported for values
   ``'quicksort'`` and ``'mergesort'``)
 * :func:`numpy.array` (only the 2 first arguments)
+* :func:`numpy.asarray` (only the 2 first arguments)
 * :func:`numpy.asfortranarray` (only the first argument)
 * :func:`numpy.atleast_1d`
 * :func:`numpy.atleast_2d`

numba/targets/arraymath.py

@@ -2523,3 +2523,34 @@ def impl(a, v):
             return _np_correlate_core(a, v[::-1], Mode.FULL, 1)
 
     return impl
+
+def _is_nonelike(ty):
+    return (ty is None) or isinstance(ty, types.NoneType)
+
+@overload(np.asarray)
+def np_asarray(a, dtype=None):
+    impl = None
+    if isinstance(a, types.Array):
+        if _is_nonelike(dtype) or a.dtype == dtype.dtype:
+            def impl(a, dtype=None):
+                return a
+        else:
+            def impl(a, dtype=None):
+                return a.astype(dtype)
+    elif isinstance(a, (types.Sequence, types.Tuple)):
+        # Nested lists cannot be unpacked, therefore only single lists are
+        # permitted and these conform to Sequence and can be unpacked along on
+        # the same path as Tuple.
+        if _is_nonelike(dtype):
+            def impl(a, dtype=None):
+                return np.array(a)
+        else:
+            def impl(a, dtype=None):
+                return np.array(a, dtype)
+    elif isinstance(a, (types.Float, types.Integer, types.Boolean)):
+        dt_conv = a if _is_nonelike(dtype) else dtype
+        ty = as_dtype(dt_conv)
+        def impl(a, dtype=None):
+                return np.array(a, ty)
+
+    return impl

numba/tests/test_np_functions.py

@@ -113,6 +113,12 @@ def corrcoef(x, y=None, rowvar=True):
 def ediff1d(ary, to_end=None, to_begin=None):
     return np.ediff1d(ary, to_end, to_begin)
 
+def asarray(a):
+    return np.asarray(a)
+
+def asarray_kws(a, dtype):
+    return np.asarray(a, dtype=dtype)
+
 
 class TestNPFunctions(MemoryLeakMixin, TestCase):
     """
@@ -1543,6 +1549,71 @@ def test_ediff1d_exceptions(self):
         assert msg in str(e.exception)
 
 
+    def test_asarray(self):
+
+        def input_variations():
+            """
+            To quote from: https://docs.scipy.org/doc/numpy/reference/generated/numpy.asarray.html
+            Input data, in any form that can be converted to an array.
+            This includes:
+            * lists
+            * lists of tuples
+            * tuples
+            * tuples of tuples
+            * tuples of lists
+            * ndarrays
+            """
+            yield 1
+            yield [1, 2, 3]
+            yield [(1, 2, 3), (1, 2, 3)]
+            yield (1, 2, 3)
+            yield ((1, 2, 3), (1, 2, 3))
+            yield ([1, 2, 3], [1, 2, 3])
+            yield np.array([])
+            yield np.arange(4)
+            yield np.arange(12).reshape(3, 4)
+            yield np.arange(12).reshape(3, 4).T
+
+        # used to check that if the input is already an array and the dtype is
+        # the same as that of the input/omitted then the array itself is
+        # returned.
+        def check_pass_through(jitted, expect_same, params):
+            returned = jitted(**params)
+            if expect_same:
+                self.assertTrue(returned is params['a'])
+            else:
+                self.assertTrue(returned is not params['a'])
+                # should be numerically the same, just different dtype
+                np.testing.assert_allclose(returned, params['a'])
+                self.assertTrue(returned.dtype == params['dtype'])
+
+        for pyfunc in [asarray, asarray_kws]:
+            cfunc = jit(nopython=True)(pyfunc)
+            _check = partial(self._check_output, pyfunc, cfunc)
+
+            for x in input_variations():
+                params = {'a': x}
+                if 'kws' in pyfunc.__name__:
+                    for dt in [None, np.complex128]:
+                        params['dtype'] = dt
+                        _check(params)
+                else:
+                    _check(params)
+
+                # check the behaviour over a dtype change (or not!)
+                x = np.arange(10, dtype=np.float32)
+                params = {'a': x}
+                if 'kws' in pyfunc.__name__:
+                    params['dtype'] = None
+                    check_pass_through(cfunc, True, params)
+                    params['dtype'] = np.complex128
+                    check_pass_through(cfunc, False, params)
+                    params['dtype'] = np.float32
+                    check_pass_through(cfunc, True, params)
+                else:
+                    check_pass_through(cfunc, True, params)
+
+
 class TestNPMachineParameters(TestCase):
     # tests np.finfo, np.iinfo, np.MachAr