nipype JoinNode test

wftest.py

import nipype.pipeline.engine as pe
from nipype.interfaces.utility import Function

def func_A(subject):
    return '%s --> [A]'%subject
def func_B(subject, in_file):
    return '%s --> B[%s]'%(subject,in_file)
def func_C(in_file):
    return '%s --> [C]'%in_file
def func_D(in_files):
    for n, file in enumerate(in_files,start=1):
        print '(join) %s. %s --> [D]'%(n, file)
    return '%s --> [D]'%in_files

a = pe.Node(interface=Function(input_names=["subject"], output_names=["subject"], function=func_A), name="A")
a.inputs.subject = 'subject 1'
b = pe.Node(interface=Function(input_names=["subject", "in_file"], output_names=["out_file"], function=func_B), name="B")
b.iterables = ("in_file", ["file%s"%n for n in (1,2,3,4)])
c = pe.Node(interface=Function(input_names=["in_file"], output_names=["out_file"], function=func_C), name="C")
d = pe.JoinNode(interface=Function(input_names=["in_files"], output_names=["output"], function=func_D), joinsource="B",
                joinfield="in_files", name="D")

my_workflow = pe.Workflow(name="my_workflow")
my_workflow.connect([(a,b,[("subject","subject")]),
                     (b,c,[("out_file","in_file")]),
                     (c,d,[("out_file","in_files")]),
                     ])
my_workflow.run()