Better handling of column lines with all values at NA

python/obitools3/dms/column/column.pyx

@@ -491,7 +491,7 @@ cdef class Column_multi_elts(Column) :
         cdef object values_iter
         if not self.active() :
             raise OBIDeactivatedInstanceError()
-        if values is None or len(values) == 0 :
+        if values is None or len(values) == 0 or (isinstance(values, Column_line) and values.is_NA()):
             for element_name in self._elements_names :
                 self.set_item(line_nb, element_name, None)
         else :
@@ -540,6 +540,10 @@ cdef class Column_line :
         return str(self._column.get_line(self._index))
  
  
+    def is_NA(self):
+        return self._column.get_line(self._index) is None
+    
+    
     def __iter__(self) :
         cdef list  elements_names
         cdef bytes element_name
@@ -569,6 +573,8 @@ cdef class Column_line :
     def __str__(self):
         cdef dict d
         cdef str  s
+        if self.is_NA():
+            return ""
         d = {}
         for k,v in self.items():
             if type(v) == bytes:

python/obitools3/format/header.pyx

@@ -56,9 +56,11 @@ cdef class HeaderFormat:
         for k in ktags:
             if k in tags:
                 value = data[k]
-                if value is None:
+                if value is None or (isinstance(value, Column_line) and value.is_NA()):
                     if self.printNAKeys:
                         value = self.NAString
+                    else:
+                        value = None
                 else:
                     if type(value) == Column_line:
                         value = value.bytes()