Write subcortical data to NIFTI files representing the data values,
subcortical structure labels, and volumetric mask. The input formats of
subcortVol, subcortLabs, and subcortMask
correspond to the data structures of xifti$data$subcort,
xifti$meta$subcort$labels , and xifti$meta$subcort$mask
respectively. subcortVol and subcortLabs should be vectorized,
so if they are volumes consider using RNifti::writeNIfTI.
write_subcort_nifti(
  subcortVol,
  subcortLabs,
  subcortMask,
  trans_mat = NULL,
  trans_units = NULL,
  col_names = NULL,
  label_table = NULL,
  subcortVol_fname,
  subcortLabs_fname,
  ROIsubcortVol_fname = NULL,
  fill = 0
)Named character vector with the "subcortVol",
"subcortLabs", and "ROIsubcortVol" file names (if written)
A vectorized data matrix: V voxels by T measurements
Numeric (0 and 3-22) or factor vector corresponding to
subcortical structure labels. See substructure_table.
Logical volumetric mask. Values of 0 represent out-of-mask voxels (not subcortical), and values of 1 represent in-mask voxels (subcortical),
The TransformationMatrixIJKtoXYZ, or equivalently the desired
sform matrix (srow_x, srow_y and srow_z) to write. If NULL, do not
write it (all zeroes).
The units of trans_mat. Currently not used.
(Optional) Column names.
(Optional) data.frame of labels and their colors.
File path to
a NIFTI to save the corresponding data. ROIsubcortVol_fname is
optional but the rest is required.
Values to use for out-of-mask voxels. Default: 0.
This function interfaces with the "-volume-label-import" Workbench
Command.
All file path arguments are required except ROIsubcortVol_fname. If
not provided, the volumetric mask will not be written. (It's redundant with
the 0 values in subcortLabs_fname because valid labels have positive
indexes.)
Note that for label data (i.e. if label_table is provided) only one
label table can be saved.
Other writing: 
separate_cifti(),
write_cifti(),
write_metric_gifti(),
write_surf_gifti(),
write_xifti2()