Construct a pushdown-aware NIfTI array source

The descriptor reads headers and one mask at construction, but no fMRI volumes. Numerical reads split requested global observations by file, pass local volume indices into neuroim2::read_vec(), and restrict the mask to requested packed features before materialization. Native reads return full-volume NeuroVec objects in requested observation order.

Usage

nifti_array_source(paths, mask, chunks = NULL)

Arguments

paths

One or more NIfTI files with a common spatial grid.

mask

A NIfTI mask path or a compatible volume_space.

chunks

Optional logical observation-by-feature chunk hint.

Value

A serializable nifti_array_source.

Details

The fingerprint covers the descriptor and the size and modification time of every file captured at construction, never the voxel values. Every open, read, and native read re-observes those files first and raises fmridataset_error_source_stale (with source, expected, actual, and changed fields) if any differ; genuine read failures remain fmridataset_error_backend_io. See content_hash() to identify values.

Examples

# A small NIfTI fixture shipped with neuroim2 stands in for real data.
path <- system.file("extdata", "global_mask_v4.nii", package = "neuroim2")
if (nzchar(path)) {
  src <- nifti_array_source(path, path)
  source_shape(src)
  source_dtype(src)
}
#> [1] "float32"