ROISurface-class | R Documentation |
A class that respresents a surface-based region of interest
The ROISurface class provides a way to represent a specific subset of vertices on a brain surface along with their associated data values. This is particularly useful for analyzing or visualizing specific anatomical or functional regions on the cortical surface.
The class maintains a reference to the complete parent surface geometry while storing
only the relevant subset of vertices, their coordinates, and their data values. The
indices
slot allows mapping back to the original vertex indices in the parent
surface.
Typical use cases include:
Extracting and analyzing data from anatomical regions of interest
Working with functional clusters identified in analyses
Isolating specific surface features for detailed investigation
Statistical analysis of data within defined surface regions
geometry
the geometry of the parent surface: a SurfaceGeometry
instance
data
the vector-valued numeric
data stored in ROI
coords
the surface-based coordinates of the data
indices
the node indices of the parent surface stored in the geometry
field.
# Create a simple tetrahedron mesh for the example
vertices <- c(
0, 0, 0,
1, 0, 0,
0, 1, 0,
0, 0, 1
)
triangles <- c(
1, 2, 3,
1, 2, 4,
1, 3, 4,
2, 3, 4
)
# Create mesh3d object
mesh <- rgl::mesh3d(vertices = vertices, triangles = triangles)
# Create a graph representation
edges <- rbind(
c(1,2), c(1,3), c(1,4),
c(2,3), c(2,4),
c(3,4)
)
graph <- igraph::graph_from_edgelist(edges)
# Create a SurfaceGeometry object
geometry <- new("SurfaceGeometry",
mesh = mesh,
graph = graph,
hemi = "left")
# Define the ROI - just using vertices 1 and 2 as an example
roi_indices <- c(1L, 2L)
# Extract coordinates for these vertices
roi_coords <- matrix(
c(0, 0, 0, # coordinates for vertex 1
1, 0, 0), # coordinates for vertex 2
ncol = 3, byrow = TRUE
)
# Create data values for the ROI vertices
roi_data <- c(0.75, 1.25) # example values for the two vertices
# Create the ROISurface object
roi <- new("ROISurface",
geometry = geometry,
data = roi_data,
coords = roi_coords,
indices = roi_indices)
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