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# sMRI: FreeSurfer

This script, smri_freesurfer.py, demonstrates the ability to call reconall on a set of subjects and then make an average subject.

> python smri_freesurfer.py

Import necessary modules from nipype.

    import os

    import nipype.pipeline.engine as pe
    import nipype.interfaces.io as nio
    from nipype.interfaces.freesurfer.preprocess import ReconAll
    from nipype.interfaces.freesurfer.utils import MakeAverageSubject

    subject_list = ['s1', 's3']
    data_dir = os.path.abspath('data')
    subjects_dir = os.path.abspath('amri_freesurfer_tutorial/subjects_dir')

    wf = pe.Workflow(name="l1workflow")
    wf.base_dir = os.path.abspath('amri_freesurfer_tutorial/workdir')

Grab data

    datasource = pe.MapNode(interface=nio.DataGrabber(infields=['subject_id'],
                                                      outfields=['struct']),
                            name='datasource',
                            iterfield=['subject_id'])
    datasource.inputs.base_directory = data_dir
    datasource.inputs.template = '%s/%s.nii'
    datasource.inputs.template_args = dict(struct=[['subject_id', 'struct']])
    datasource.inputs.subject_id = subject_list

Run recon-all

    recon_all = pe.MapNode(interface=ReconAll(), name='recon_all',
                           iterfield=['subject_id', 'T1_files'])
    recon_all.inputs.subject_id = subject_list
    if not os.path.exists(subjects_dir):
        os.mkdir(subjects_dir)
    recon_all.inputs.subjects_dir = subjects_dir

    wf.connect(datasource, 'struct', recon_all, 'T1_files')

Make average subject

    average = pe.Node(interface=MakeAverageSubject(), name="average")
    average.inputs.subjects_dir = subjects_dir

    wf.connect(recon_all, 'subject_id', average, 'subjects_ids')

    wf.run("MultiProc", plugin_args={'n_procs': 4})

Example source code

You can download `the full source code of this example`. This same script is also included in the Nipype source distribution under the `examples` directory.