MAINT: Cleaned up mintypecode for Py3

Using generators instead of full-blown lists
Using set for search instead of list
Using min to get single element insteaf of sorting full list

numpy/lib/type_check.py

@@ -75,7 +75,7 @@ def mintypecode(typechars, typeset='GDFgdf', default='d'):
         return default
     if 'F' in intersection and 'd' in intersection:
         return 'D'
-    return min((_typecodes_by_elsize.index(t), t) for t in intersection)[1]
+    return min(intersection, key=_typecodes_by_elsize.index)
 
 
 def _asfarray_dispatcher(a, dtype=None):