Signature Description Parameters
template<typename RHS_T, typename ... Ts>
StdDataFrame<IndexType>
concat(const RHS_T &rhs, concat_policy cp = concat_policy::all_columns) const;
It concatenates rhs to the end of self and returns the result as another DataFrame.
Concatenation is done based on policy
RHS_T: Type of DataFrame rhs
Ts: List all the types of all data columns. A type should be specified in the list only once.
rhs: The rhs DataFrame
cp: Concatenation policy:
          all_columns: concatenate all columns. If a column does not exist in self,
          create one in the result and prepend with nan
          common_columns: only apply concatenation to the common columns
          lhs_and_common_columns: the result will have all the columns in self,
          but only common columns and index are concatenated
        
      
template<typename RHS_T, typename ... Ts>
void
self_concat(const RHS_T &rhs, bool add_new_columns = true);
This is similar to concat() method but it is applied to self. It changes self. RHS_T: Type of DataFrame rhs
Ts: List all the types of all data columns. A type should be specified in the list only once.
rhs: The rhs DataFrame
add_new_columns: If true, it creates new columns in self and prepend them with nan