Можно ли объединить суммирование с summarise_at в одном group_by с dplyr

import java.util.Stack;

class Demo
{

    char c;

    public  boolean checkParan(String word)
    {
        Stack<Character> sta = new Stack<Character>();
        for(int i=0;i<word.length();i++)
        {
           c=word.charAt(i);


          if(c=='(')
          {
              sta.push(c);
              System.out.println("( Pushed into the stack");

          }
          else if(c=='{')
          {
              sta.push(c);
              System.out.println("( Pushed into the stack");
          }
          else if(c==')')
          {
              if(sta.empty())
              {
                  System.out.println("Stack is Empty");
                  return false;
              }
              else if(sta.peek()=='(')
              {

                  sta.pop();
                  System.out.println(" ) is poped from the Stack");
              }
              else if(sta.peek()=='(' && sta.empty())
              {
                  System.out.println("Stack is Empty");
                  return false;
              }
          }
          else if(c=='}')
          {
              if(sta.empty())
              {
               System.out.println("Stack is Empty");
              return false;
              }
              else if(sta.peek()=='{')
              {
                  sta.pop();
                  System.out.println(" } is poped from the Stack");
              }

          }

          else if(c=='(')
          {
              if(sta.empty())
              {
                 System.out.println("Stack is empty only ( parenthesis in Stack ");  
              }
          }


        }
    // System.out.print("The top element is : "+sta.peek());
    return sta.empty();
    } 





}

public class ParaenthesisChehck {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic here
       Demo d1= new Demo();
     //  d1.checkParan(" ");
      // d1.checkParan("{}");
       //d1.checkParan("()");
       //d1.checkParan("{()}");
     // d1.checkParan("{123}");
       d1.checkParan("{{{}}");





    }

}