REVIEW: simplified an expression

src/caosadvancedtools/table_importer.py

@@ -96,9 +96,9 @@ class XLS_Importer(object):
         df = df.copy()
         uniques = []
 
-        for index, row in df.iterrows():
-            element = tuple(row.loc[key] for key in self.unique_columns)
-
+        subtable = df[list(self.unique_columns)]
+        for index, row in subtable.iterrows():
+            element = tuple(row)
             if element in uniques:
                 errmssg = (
                     "The {}. row contains the values '{}'.\nThis value "