edge_asymmetry {brainGraph} | R Documentation |
Calculate an asymmetry index based on edge counts
Description
Calculate an asymmetry index, a ratio of intra-hemispheric edges in the left to right hemisphere of a graph for brain MRI data.
Usage
edge_asymmetry(g, level = c("hemi", "vertex"), A = NULL)
Arguments
g |
An |
level |
Character string indicating whether to calculate asymmetry for
each region, or the hemisphere as a whole (default: |
A |
Numeric matrix; the adjacency matrix of the input graph. Default:
|
Details
The equation is:
where lh and rh are left and right hemispheres, respectively.
The range of this measure is (although the limits will only be
reached if all edges are in one hemisphere), with negative numbers
indicating more edges in the right hemisphere, and a value of 0 indicating
equal number of edges in each hemisphere.
The level
argument specifies whether to calculate asymmetry for each
vertex, or for the whole hemisphere.
Value
A data table with edge counts for both hemispheres and the asymmetry
index; if level
is vertex, the data table will have
vcount(g)
rows.
Author(s)
Christopher G. Watson, cgwatson@bu.edu