Convert DenseNeuroVec to sparse representation using mask

This method converts a DenseNeuroVec object to a sparse representation using a given LogicalNeuroVol mask.

This method converts a DenseNeuroVec object to a sparse representation using a given numeric mask.

Usage

# S4 method for class 'DenseNeuroVec,LogicalNeuroVol'
as.sparse(x, mask)

# S4 method for class 'DenseNeuroVec,numeric'
as.sparse(x, mask)

# S4 method for class 'DenseNeuroVol,LogicalNeuroVol'
as.sparse(x, mask)

# S4 method for class 'DenseNeuroVol,numeric'
as.sparse(x, mask)

# S4 method for class 'ROIVol,ANY'
as.sparse(x)

Arguments

x

A DenseNeuroVec object to convert to a sparse representation.

mask

A numeric vector representing the mask to apply during conversion.

Value

A SparseNeuroVec object resulting from the conversion.

A SparseNeuroVec object resulting from the conversion.

Details

For a DenseNeuroVec, numeric masks use R's vector-indexing rules: positive indices retain voxels, negative indices exclude voxels, and zeros are ignored. Repeated indices retain a voxel once. Retained voxels are stored in ascending spatial-index order, regardless of the order supplied in mask. An empty selection produces an all-zero sparse image with the original dimensions. Missing or non-finite indices and positive indices outside the spatial extent are rejected.