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Example 1

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 2

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 3

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 4

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 5

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 6

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 7

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 8

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 9

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 10

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 11

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 12

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 13

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 14

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 15

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 16

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 17

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 18

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 19

def test_iter_nested_iters_basic():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 20

def test_iter_nested_iters_broadcast():
    # Test nested iteration with broadcasting
    a = arange(2).reshape(2, 1)
    b = arange(3).reshape(1, 3)

    i, j = np.nested_iters([a, b], [[0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]]])

    i, j = np.nested_iters([a, b], [[1], [0]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[[0, 0], [1, 0]], [[0, 1], [1, 1]], [[0, 2], [1, 2]]]) 

Example 21

def test_0d_nested_iter():
    a = np.arange(12).reshape(2, 3, 2)
    i, j = np.nested_iters(a, [[], [1, 0, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0, 2], []])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0], [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11]])

    i, j, k = np.nested_iters(a, [[2, 0], [], [1]])
    vals = []
    for x in i:
        for y in j:
            vals.append([z for z in k])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]]) 

Example 22

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 23

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 24

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 25

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 26

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 27

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 28

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 29

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 30

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 31

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 32

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 33

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 34

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 35

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 36

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 37

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 38

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 39

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]]) 

Example 40

def test_iter_nested_iters_reorder():
    # Test nested iteration basic usage
    a = arange(12).reshape(2, 3, 2)

    # In 'K' order (default), it gets reordered
    i, j = np.nested_iters(a, [[0], [2, 1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, it doesn't
    i, j = np.nested_iters(a, [[0], [2, 1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4, 1, 3, 5], [6, 8, 10, 7, 9, 11]])

    i, j = np.nested_iters(a, [[1, 0], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [6, 7], [2, 3], [8, 9], [4, 5], [10, 11]])

    i, j = np.nested_iters(a, [[2, 0], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [6, 8, 10], [1, 3, 5], [7, 9, 11]]) 

Example 41

def test_iter_nested_iters_flip_axes():
    # Test nested iteration with negative axes
    a = arange(12).reshape(2, 3, 2)[::-1, ::-1, ::-1]

    # In 'K' order (default), the axes all get flipped
    i, j = np.nested_iters(a, [[0], [1, 2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2, 3, 4, 5], [6, 7, 8, 9, 10, 11]])

    i, j = np.nested_iters(a, [[0, 1], [2]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1], [2, 3], [4, 5], [6, 7], [8, 9], [10, 11]])

    i, j = np.nested_iters(a, [[0, 2], [1]])
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 2, 4], [1, 3, 5], [6, 8, 10], [7, 9, 11]])

    # In 'C' order, flipping axes is disabled
    i, j = np.nested_iters(a, [[0], [1, 2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10, 9, 8, 7, 6], [5, 4, 3, 2, 1, 0]])

    i, j = np.nested_iters(a, [[0, 1], [2]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 10], [9, 8], [7, 6], [5, 4], [3, 2], [1, 0]])

    i, j = np.nested_iters(a, [[0, 2], [1]], order='C')
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[11, 9, 7], [10, 8, 6], [5, 3, 1], [4, 2, 0]]) 

Example 42

def test_iter_nested_iters_dtype_copy():
    # Test nested iteration with a copy to change dtype

    # copy
    a = arange(6, dtype='i4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readonly', 'copy'],
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    vals = []
    for x in i:
        vals.append([y for y in j])
    assert_equal(vals, [[0, 1, 2], [3, 4, 5]])
    vals = None

    # updateifcopy
    a = arange(6, dtype='f4').reshape(2, 3)
    i, j = np.nested_iters(a, [[0], [1]],
                        op_flags=['readwrite', 'updateifcopy'],
                        casting='same_kind',
                        op_dtypes='f8')
    assert_equal(j[0].dtype, np.dtype('f8'))
    for x in i:
        for y in j:
            y[...] += 1
    assert_equal(a, [[0, 1, 2], [3, 4, 5]])
    i, j, x, y = (None,)*4  # force the updateifcopy
    assert_equal(a, [[1, 2, 3], [4, 5, 6]])