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Plot the vertex-wise difference between two scalar maps

Source: R/plot_vw_diff.R
plot_vw_diff.Rd

Computes the vertex-wise difference (a - b) between two surface maps (numeric vectors or MGH/GII file paths) for each hemisphere, then renders the result on a standard fsaverage surface via plot_vw_surf().

Useful for contrasting two conditions, time-points, groups, or model terms without pre-computing the difference outside R.

Usage

plot_vw_diff(
  lh_a = NULL,
  lh_b = NULL,
  rh_a = NULL,
  rh_b = NULL,
  label_a = "a",
  label_b = "b",
  ...
)

Arguments

lh_a, lh_b

Left-hemisphere map: numeric vector or path to an MGH/GII file. Both must have the same length / vertex count. Pass NULL to omit the left hemisphere entirely.

rh_a, rh_b

Right-hemisphere map: same as above for the right hemisphere. Pass NULL to omit the right hemisphere.

label_a, label_b

Short character labels used in the default figure title (e.g. "group A", "group B"). Ignored when title is supplied via ....

...

Additional arguments forwarded to plot_vw_surf(), e.g. roi_outline, views, cmap, vmin, vmax, colorbar, colorbar_label, title, to_file, dpi, fs_home, fs_template.

Value

Invisibly: the output of plot_vw_surf() — the temp HTML file path (interactive mode) or to_file path (static PNG mode). Called primarily for its side-effect of opening or saving the figure.

See also

plot_vw_surf(), plot_vw_map() vw_diff()

Examples

if (FALSE) { # rlang::is_installed("reticulate") && dir.exists("path/to/model1/")
# Two numeric vectors
plot_vw_diff(
  lh_a = lh_term1, lh_b = lh_term2,
  rh_a = rh_term1, rh_b = rh_term2,
  label_a = "Term 1", label_b = "Term 2",
  cmap = "RdBu_r"
)

# Two MGH files, left hemisphere only
plot_vw_diff(
  lh_a = "path/to/model1/lh.area.aic.mgh",
  lh_b = "path/to/model2/lh.area.aic.mgh",
  label_a = "model1", label_b = "model2"
)
}