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python: fix bytes() on non-contiguous arrays #4449

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Merged
zcbenz merged 2 commits into from
Sep 10, 2026
+12 −2
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python: fix bytes() on non-contiguous arrays #4449

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python: fix bytes() on non-contiguous arrays
axiom-of-choice Sep 1, 2026
ea4bccd
tests: add test for bytes() on non-contiguous arrays
axiom-of-choice Sep 10, 2026
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5 changes: 3 additions & 2 deletions python/src/array.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1046,9 +1046,10 @@ void init_array(nb::module_& m) {
.def(
"__bytes__",
[](mx::array& a) {
a.eval();
auto c = mx::contiguous(a);

@simeetnayan81 simeetnayan81 Sep 1, 2026

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Won't this be better? We might want to save a second call if a is already packed/contiguous :

a.flags().row_contiguous ? a : mx::contiguous(a);

@zcbenz zcbenz Sep 2, 2026

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When a is not evaluated a.flags().row_contiguous would return garbage so we have to use mx::contiguous.

@simeetnayan81 simeetnayan81 Sep 2, 2026

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Oh alright. Then we may skip this. Thanks.

c.eval();
return nb::bytes(
reinterpret_cast<const char*>(a.data<void>()), a.nbytes());
reinterpret_cast<const char*>(c.data<void>()), c.nbytes());
})
.def(
"__format__",
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9 changes: 9 additions & 0 deletions python/tests/test_array.py
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Expand Up @@ -2042,6 +2042,15 @@ def test_buffer_protocol(self):
self.assertEqual(b"aaaaaaaaaa", ab[::2])
self.assertEqual(b"abcdefghij", ab[1::2])

# Test bytes on non-contiguous arrays
a = mx.arange(10, dtype=mx.uint8)
self.assertEqual(bytes(a[::2]), b"\x00\x02\x04\x06\x08")
self.assertEqual(bytes(a[::-1]), b"\x09\x08\x07\x06\x05\x04\x03\x02\x01\x00")
b = mx.arange(6, dtype=mx.int32).reshape(2, 3).T
self.assertEqual(bytes(b), np.array(b).tobytes())
c = mx.broadcast_to(mx.array([1, 2], dtype=mx.uint8), (3, 2))
self.assertEqual(bytes(c), np.array(c).tobytes())

def test_buffer_protocol_ref_counting(self):
a = mx.arange(3)
wr = weakref.ref(a)
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