Rename example20 -> example-numpy-dtypes

example/example-numpy-dtypes.py

@@ -0,0 +1,83 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+import unittest
+import numpy as np
+from example import (
+    create_rec_simple, create_rec_packed, create_rec_nested, print_format_descriptors,
+    print_rec_simple, print_rec_packed, print_rec_nested, print_dtypes, get_format_unbound,
+    create_rec_partial, create_rec_partial_nested, create_string_array, print_string_array
+)
+
+
+def check_eq(arr, data, dtype):
+    np.testing.assert_equal(arr, np.array(data, dtype=dtype))
+
+unittest.TestCase().assertRaisesRegex(
+    RuntimeError, 'unsupported buffer format', get_format_unbound)
+
+print_format_descriptors()
+print_dtypes()
+
+simple_dtype = np.dtype({'names': ['x', 'y', 'z'],
+                         'formats': ['?', 'u4', 'f4'],
+                         'offsets': [0, 4, 8]})
+packed_dtype = np.dtype([('x', '?'), ('y', 'u4'), ('z', 'f4')])
+
+elements = [(False, 0, 0.0), (True, 1, 1.5), (False, 2, 3.0)]
+
+for func, dtype in [(create_rec_simple, simple_dtype), (create_rec_packed, packed_dtype)]:
+    arr = func(0)
+    assert arr.dtype == dtype
+    check_eq(arr, [], simple_dtype)
+    check_eq(arr, [], packed_dtype)
+
+    arr = func(3)
+    assert arr.dtype == dtype
+    check_eq(arr, elements, simple_dtype)
+    check_eq(arr, elements, packed_dtype)
+
+    if dtype == simple_dtype:
+        print_rec_simple(arr)
+    else:
+        print_rec_packed(arr)
+
+
+arr = create_rec_partial(3)
+print(arr.dtype)
+partial_dtype = arr.dtype
+assert '' not in arr.dtype.fields
+assert partial_dtype.itemsize > simple_dtype.itemsize
+check_eq(arr, elements, simple_dtype)
+check_eq(arr, elements, packed_dtype)
+
+arr = create_rec_partial_nested(3)
+print(arr.dtype)
+assert '' not in arr.dtype.fields
+assert '' not in arr.dtype.fields['a'][0].fields
+assert arr.dtype.itemsize > partial_dtype.itemsize
+np.testing.assert_equal(arr['a'], create_rec_partial(3))
+
+nested_dtype = np.dtype([('a', simple_dtype), ('b', packed_dtype)])
+
+arr = create_rec_nested(0)
+assert arr.dtype == nested_dtype
+check_eq(arr, [], nested_dtype)
+
+arr = create_rec_nested(3)
+assert arr.dtype == nested_dtype
+check_eq(arr, [((False, 0, 0.0), (True, 1, 1.5)),
+               ((True, 1, 1.5), (False, 2, 3.0)),
+               ((False, 2, 3.0), (True, 3, 4.5))], nested_dtype)
+print_rec_nested(arr)
+
+assert create_rec_nested.__doc__.strip().endswith('numpy.ndarray[dtype=NestedStruct]')
+
+arr = create_string_array(True)
+print(arr.dtype)
+print_string_array(arr)
+dtype = arr.dtype
+assert arr['a'].tolist() == [b'', b'a', b'ab', b'abc']
+assert arr['b'].tolist() == [b'', b'a', b'ab', b'abc']
+arr = create_string_array(False)
+assert dtype == arr.dtype