allfromall.py

import nipype.interfaces.io as nio
import nipype.pipeline.engine as pe
volsource = pe.Node(interface = nio.DataGrabber(outfields=["dw_imgs"]), name="volsource")
project_dir = "/mindhive/gablab/sad/PY_STUDY_DIR/Block"
volsource.inputs.base_directory = project_dir
volsource.inputs.template = "diffusion/preproc/SAD_*/%s_warp.nii.gz"
volsource.base_dir = '.'
volsource.inputs.template_args = dict(dw_imgs=[[["fa", "ra", "adc"]]])
res = volsource.run()

allfromone.py

subject_list = ['SAD_P07'] #using single subject as demo, just add all subjects to the list

node = pe.Node(interface=utils.IdentityInterface(fields=['subject_id']), name='subjectid')
node.iterables = ('subject_id', subject_list)

volsource = pe.Node(interface = nio.DataGrabber(infields=['subject_id'], outfields=["dw_imgs"]), name="volsource")
project_dir = "/mindhive/gablab/sad/PY_STUDY_DIR/Block"
volsource.inputs.base_directory = project_dir
volsource.inputs.template = "diffusion/preproc/%s/%s_warp.nii.gz"
volsource.inputs.template_args = dict(dw_imgs=[['subject_id', ["fa", "ra", "adc"]]])

workflow = pe.Workflow(name='getdata')
workflow.connect(node, 'subject_id', volsource, 'subject_id')
workflow.run()