Make sure only data columns are returned in corr; Newer versions of CAS return missing value info

Author: Kevin D Smith

swat/cas/table.py

@@ -2878,7 +2878,9 @@ def corr(self, method=None, min_periods=None):
         out = tbl._retrieve('simple.correlation', simple=False)['Correlation']
         out.set_index('Variable', inplace=True)
         out.index.name = None
-        return out
+        # Newer versions of the CAS server return extra columns
+        # containing missing value information.
+        return out[tbl.columns]
 
 #   def corrwith(self, other, axis=None, drop=None):
 #       raise NotImplementedError