ENH: Enable Merge(0) to merge a list of lists

Author: effigies

nipype/interfaces/utility/base.py

@@ -128,24 +128,38 @@ class Merge(IOBase):
  def __init__(self, numinputs=0, **inputs):
  super(Merge, self).__init__(**inputs)
  self._numinputs = numinputs
- add_traits(self.inputs, ['in%d' % (i + 1) for i in range(numinputs)])
+ if numinputs > 0:
+ input_names = ['in%d' % (i + 1) for i in range(numinputs)]
+ elif numinputs == 0:
+ input_names = ['in_lists']
+ else:
+ input_names = []
+ add_traits(self.inputs, input_names)
 
  def _list_outputs(self):
  outputs = self._outputs().get()
  out = []
+
+ if self._numinputs == 0:
+ values = getattr(self.inputs, 'in_lists')
+ if not isdefined(values):
+ return outputs
+ else:
+ getval = lambda idx: getattr(self.inputs, 'in%d' % (idx + 1))
+ values = [getval(idx) for idx in range(self._numinputs)
+ if isdefined(getval(idx))]
+
  if self.inputs.axis == 'vstack':
- for idx in range(self._numinputs):
- value = getattr(self.inputs, 'in%d' % (idx + 1))
- if isdefined(value):
- if isinstance(value, list) and not self.inputs.no_flatten:
- out.extend(value)
- else:
- out.append(value)
+ for value in values:
+ if isinstance(value, list) and not self.inputs.no_flatten:
+ out.extend(value)
+ else:
+ out.append(value)
  else:
- for i in range(len(filename_to_list(self.inputs.in1))):
+ for i in range(len(filename_to_list(values[0]))):
  out.insert(i, [])
- for j in range(self._numinputs):
- out[i].append(filename_to_list(getattr(self.inputs, 'in%d' % (j + 1)))[i])
+ for value in values:
+ out[i].append(filename_to_list(value)[i])
  if out:
  outputs['out'] = out
  return outputs

nipype/interfaces/utility/tests/test_base.py

@@ -55,23 +55,32 @@ def test_split(tmpdir, args, expected):
 @pytest.mark.parametrize("args, kwargs, in_lists, expected", [
  ([3], {}, [0, [1, 2], [3, 4, 5]], [0, 1, 2, 3, 4, 5]),
  ([], {}, None, None),
+ ([], {}, [0, [1, 2], [3, 4, 5]], [0, 1, 2, 3, 4, 5]),
  ([3], {'axis': 'hstack'}, [[0], [1, 2], [3, 4, 5]], [[0, 1, 3]]),
  ([3], {'axis': 'hstack'}, [[0, 1], [2, 3], [4, 5]],
  [[0, 2, 4], [1, 3, 5]]),
  ([3], {'axis': 'hstack'}, [[0, 1], [2, 3], [4, 5]],
  [[0, 2, 4], [1, 3, 5]]),
+ # Note: Merge(0, axis='hstack') would error on run, prior to
+ # in_lists implementation
+ ([0], {'axis': 'hstack'}, [[0], [1, 2], [3, 4, 5]], [[0, 1, 3]]),
+ ([0], {'axis': 'hstack'}, [[0, 1], [2, 3], [4, 5]],
+ [[0, 2, 4], [1, 3, 5]]),
  ])
 def test_merge(tmpdir, args, kwargs, in_lists, expected):
  os.chdir(str(tmpdir))
 
  node = pe.Node(utility.Merge(*args, **kwargs), name='merge')
 
  numinputs = args[0] if args else 0
- for i in range(1, numinputs + 1):
- setattr(node.inputs, 'in{:d}'.format(i), in_lists[i - 1])
+ if numinputs == 0 and in_lists:
+ node.inputs.in_lists = in_lists
+ else:
+ for i in range(1, numinputs + 1):
+ setattr(node.inputs, 'in{:d}'.format(i), in_lists[i - 1])
 
  res = node.run()
- if numinputs == 0:
+ if numinputs == 0 and in_lists is None:
  assert not isdefined(res.outputs.out)
  else:
  assert res.outputs.out == expected