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fix: byteswap non-native input instead of reinterpreting it #152

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Merged
tlambert03 merged 1 commit into from
Aug 12, 2026
Merged

fix: byteswap non-native input instead of reinterpreting it #152

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3 changes: 1 addition & 2 deletions src/cmap/_colormap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -415,8 +415,7 @@ def __call__(
xa = np.array(x, copy=True)
if not xa.dtype.isnative:
# Native byteorder is faster.
native: Literal[">", "<"] = ">" if xa.dtype.byteorder in ("<", "=") else "<"
xa = xa.view(xa.dtype.newbyteorder(native))
xa = xa.byteswap().view(xa.dtype.newbyteorder())
if xa.dtype.kind == "f":
xa *= N
# xa == 1 (== N after multiplication) is not out of range.
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8 changes: 8 additions & 0 deletions tests/test_colormap.py
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,14 @@ def test_colormap_apply() -> None:
assert cmap1(swapped).shape == (10, 10, 4)


def test_non_native_byte_order_maps_the_same_colors() -> None:
cmap = Colormap(["red", "blue"], under="green", over="yellow", bad="black")
native = np.array([-0.5, 0.0, 0.5, 1.0, 1.5, np.nan])
non_native = native.astype(native.dtype.newbyteorder())

npt.assert_array_equal(cmap(non_native), cmap(native))


def test_colormap_masked_array_with_unmasked_nan() -> None:
cmap = Colormap("viridis", bad="red")
mask = [True, False, False, False]
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