changed if clause structure to account for case when single file name is given

Author: oliver-contier

nipype/workflows/fmri/fsl/preprocess.py

@@ -18,22 +18,25 @@ def getthreshop(thresh):
     return ['-thr %.10f -Tmin -bin' % (0.1 * val[1]) for val in thresh]
 
 
-
 def pickrun(files, whichrun):
     """pick file from list of files"""
 
     filemap = {'first': 0, 'last': -1, 'middle': len(files) // 2}
 
-    if isinstance(whichrun, str):
-        if whichrun not in filemap.keys():
-            raise(KeyError, 'Sorry, whichrun must be either integer index'
-                            'or string in form of "first", "last" or "middle')
-        else:
-            return files[filemap[whichrun]]
-
     if isinstance(files, list):
-        return files[whichrun]
+
+        # whichrun is given as integer
+        if isinstance(whichrun, int):
+            return files[whichrun]
+        # whichrun is given as string
+        elif isinstance(whichrun, str):
+            if whichrun not in filemap.keys():
+                raise(KeyError, 'Sorry, whichrun must be either integer index'
+                                'or string in form of "first", "last" or "middle')
+            else:
+                return files[filemap[whichrun]]
     else:
+        # in case single file name is given
         return files