Extract NeuroVol list for a specific group — extract

Convenience function that combines split.gds() and as_neurovol_list() to extract neuroimaging volumes for subjects in a specific group.

Usage

extract_group(x, group_var, group_level, assay = "beta", ...)

Arguments

x: A GDS object.
group_var: Column name in col_data(x) containing group labels.
group_level: The specific group level to extract.
assay: Name of the assay to extract (default: "beta").
...: Additional arguments passed to as_neurovol_list().

Value

A named list of neuroim2::NeuroVol objects for subjects in the specified group.

Examples

if (requireNamespace("neuroim2", quietly = TRUE)) {
  sp4 <- neuroim2::NeuroSpace(c(4, 4, 2, 4), spacing = c(2, 2, 2))
  vec4d <- neuroim2::NeuroVec(array(rnorm(128), c(4, 4, 2, 4)), sp4)
  gds <- as_gds(vec4d, along = "subject", subjects = paste0("sub0", 1:4))
  gds <- with_col_data(gds, data.frame(
    diagnosis = c("patient", "control", "patient", "control"),
    row.names = subjects(gds)
  ))

  # Get beta maps for all patients
  patient_vols <- extract_group(gds, "diagnosis", "patient", assay = "beta")
  print(names(patient_vols))

  # Get beta maps for controls
  control_vols <- extract_group(gds, "diagnosis", "control", assay = "beta")
  print(names(control_vols))
}
#> [1] "sub01" "sub03"
#> [1] "sub02" "sub04"