public static List <string> IntersectOnRowKeysShoMatrix(ref ShoMatrix m1, ref ShoMatrix m2) { IList <string> var2 = m2.RowKeys; IList <string> var1 = m1.RowKeys; List <string> var = var2.Intersect(var1).ToList(); m1 = m1.SelectRowsView(var).AsShoMatrix(); m2 = m2.SelectRowsView(var).AsShoMatrix(); return(var); }