Fix lenght to 5 characterse

Author: bobleesj

src/diffpy/structure/structure.py

@@ -711,8 +711,9 @@ def _get_composition(self):
     element = _linkAtomAttribute(
         "element",
         """Character array of `Atom` types. Assignment updates
-        the element attribute of the respective `Atoms`.""",
-        toarray=numpy.char.array,
+        the element attribute of the respective `Atoms`.
+        Set the maximum length of the element string to 5 characters.""",
+        toarray=lambda items: numpy.char.array(items, itemsize=5)
     )
 
     xyz = _linkAtomAttribute(
@@ -742,8 +743,9 @@ def _get_composition(self):
     label = _linkAtomAttribute(
         "label",
         """Character array of `Atom` names. Assignment updates
-        the label attribute of all `Atoms`.""",
-        toarray=numpy.char.array,
+        the label attribute of all `Atoms`.
+        Set the maximum length of the label string to 5 characters.""",
+        toarray=lambda items: numpy.char.array(items, itemsize=5)
     )
 
     occupancy = _linkAtomAttribute(

src/diffpy/structure/utils.py

@@ -92,7 +92,7 @@ def _linkAtomAttribute(attrname, doc, toarray=numpy.array):
     from operator import setitem
 
     _all = slice(None)
-
+    
     def fget(self):
         va = toarray([getattr(a, attrname) for a in self])
         return va