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fix(nifti): enable lazy loading for Nifti1ImageWrapper #7887

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fix(nifti): enable lazy loading for Nifti1ImageWrapper #7887

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872490c
fix(nifti): enable lazy loading for Nifti1ImageWrapper
The-Obstacle-Is-The-Way Nov 29, 2025
c706e73
chore: trigger CI
The-Obstacle-Is-The-Way Nov 29, 2025
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2 changes: 1 addition & 1 deletion src/datasets/features/nifti.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ class Nifti1ImageWrapper(nib.nifti1.Nifti1Image):

def __init__(self, nifti_image: nib.nifti1.Nifti1Image):
super().__init__(
dataobj=nifti_image.get_fdata(),
dataobj=nifti_image.dataobj,
affine=nifti_image.affine,
header=nifti_image.header,
extra=nifti_image.extra,
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19 changes: 19 additions & 0 deletions tests/features/test_nifti.py
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Expand Up @@ -128,3 +128,22 @@ def test_load_zipped_file_locally(shared_datadir):

ds = load_dataset("niftifolder", data_files=nifti_path)
assert isinstance(ds["train"][0]["nifti"], nib.nifti1.Nifti1Image)


@require_nibabel
def test_nifti_lazy_loading(shared_datadir):
import nibabel as nib
import numpy as np

nifti_path = str(shared_datadir / "test_nifti.nii.gz")
nifti = Nifti()
encoded_example = nifti.encode_example(nifti_path)
decoded_example = nifti.decode_example(encoded_example)

# Verify that the data object is an ArrayProxy (lazy) and not a numpy array (dense)
assert nib.is_proxy(decoded_example.dataobj)
assert not isinstance(decoded_example.dataobj, np.ndarray)

# Verify that we can still access the data
data = decoded_example.get_fdata()
assert data.shape == (80, 80, 10)