ENH: Override _format_arg, make specs

Author: effigies

nipype/interfaces/afni/preprocess.py

@@ -2581,6 +2581,11 @@ class Volreg(AFNICommand):
     input_spec = VolregInputSpec
     output_spec = VolregOutputSpec
 
+    def _format_arg(self, name, trait_spec, value):
+        if name == 'in_weight_volume' and not isinstance(value, Tuple):
+            value = (value, 0)
+        return super(Volreg, self)._format_arg(name, trait_spec, value)
+
 
 class WarpInputSpec(AFNICommandInputSpec):
     in_file = File(

nipype/interfaces/afni/tests/test_auto_Volreg.py

@@ -26,6 +26,7 @@ def test_Volreg_inputs():
             mandatory=True,
             position=-1,
         ),
+        in_weight_volume=dict(argstr="-weight '%s[%d]'", ),
         interp=dict(argstr='-%s', ),
         md1d_file=dict(
             argstr='-maxdisp1D %s',