TraitError: The 'luts' trait of a PicoPDFsInputSpec instance must be a list of from 1 to 3 items which are an existing file name, but a value of '/_subject_id_subj1/dtlutgen/bvecs.dat' <type 'str'> was specified.

[robbert-harms]

When trying to run the demo "dmri_camino_dti.py" I encountered the following problem with the PicoPDFsInputSpec:

TraitError: The 'luts' trait of a PicoPDFsInputSpec instance must be a list of from 1 to 3 items which are an existing file name, but a value of '/_subject_id_subj1/dtlutgen/bvecs.dat' <type 'str'> was specified.
Error setting node input:
Node: picopdfs
input: luts

I browsed through the source code and I believe that the error lies in these two code snippits which are incompatible:

from interfaces/camino.dti.py in class PicoPDFsInputSpec:

luts = traits.List(File(exists=True), argstr='-luts %s', ...)

and in the same file in class DTLUTGenOutputSpec

dtLUT = File(exists=True, desc='Lookup Table')

and the code in the script:

dtlutgen = pe.Node(interface=camino.DTLUTGen(), name="dtlutgen")
dtlutgen.inputs.snr = 16.0
dtlutgen.inputs.inversion = 1
...
picopdfs = pe.Node(interface=camino.PicoPDFs(), name="picopdfs")
picopdfs.inputs.inputmodel = 'dt'
...
tractography.connect([(dtlutgen, picopdfs,[("dtLUT","luts")])])

It seems that the PicoDFSs requires a list as input (with a file in it), while the dtlutgen gives a file as output.