IndexLookupVol-class: IndexLookupVol Class

In bbuchsbaum/neuroim2: Data Structures and IO for Neuroimaging Data with an Emphasis on Functional Magnetic Resonance Imaging (FMRI)

IndexLookupVol Class

Description

A three-dimensional brain image class that serves as a map between 1D grid indices and a table of values. This class is primarily used in conjunction with the SparseNeuroVec class to efficiently represent and access sparse neuroimaging data.

This function creates an IndexLookupVol object, which represents a lookup volume for efficient indexing of voxels in a 3D brain image space.

Usage

IndexLookupVol(space, indices)

Arguments

space	A NeuroSpace object representing the 3D space of the brain image.
indices	An integer vector containing the 1D indices of the voxels in the grid.

Details

The IndexLookupVol class extends NeuroVol and provides a mechanism for efficient lookup and mapping of sparse 3D neuroimaging data. It stores only the indices of non-zero voxels and their corresponding mappings, allowing for memory-efficient representation of large, sparse brain images.

Value

An object of class IndexLookupVol representing the index lookup volume.

Slots

space

A NeuroSpace object representing the 3D space of the brain image.

indices

An integer vector containing the 1D indices of the non-zero voxels in the grid.

map

An integer vector containing the mapping between the 1D indices and the table of values.

Methods

This class inherits methods from NeuroVol. Additional methods specific to index lookup and mapping operations may be available.

See Also

SparseNeuroVec-class for the primary class that utilizes IndexLookupVol. NeuroVol-class for the base volumetric image class.

IndexLookupVol, NeuroSpace

Examples

# Create a NeuroSpace object
space <- NeuroSpace(dim = c(2L, 2L, 2L), origin = c(0, 0, 0), spacing = c(1, 1, 1))

# Create a 3D mask
mask <- array(c(TRUE, FALSE, TRUE, FALSE, FALSE, TRUE, FALSE, TRUE), dim = c(2, 2, 2))

# Create indices and map for the IndexLookupVol
indices <- which(mask)
map <- seq_along(indices)

# Create an IndexLookupVol object
ilv <- new("IndexLookupVol", space = space, indices = as.integer(indices), map = map)

# Access the indices
print(ilv@indices)

# Access the map
print(ilv@map)

## Not run: 
space <- NeuroSpace(c(64, 64, 64), c(1, 1, 1), c(0, 0, 0))
indices <- sample(1:262144, 10000)  # Random selection of 10000 voxels
ilv <- IndexLookupVol(space, indices)

## End(Not run)

bbuchsbaum/neuroim2 documentation built on Nov. 3, 2024, 9:31 a.m.