object Main extends App {
	val emp: List[String] = List("customer_bal_history_1_36","customer_bal_history_1_36_1","customer_bal_history_1_36_2","customer_bal_history_1_36_3","customer_credit_history_37_72_1","customer_credit_history_37_72_2","customer_credit_history_37_72_3","employee_1", "employee_10", "address","pincode","domain_1","domain_2","vehicle_1","vehicle_2","vendor_account_1","vendor_account_2")
	val pattern = """^[^\d_]*_[^\d_]*_\D*_""".r
	val res = emp.foldLeft(Map[String, List[String]]()){ case (acc, name) =>
	  pattern.findFirstMatchIn(name) match {
	    case Some(ns) => acc + (ns.group(0) -> (name :: acc.getOrElse(ns.group(0), Nil)))
	    case _ => acc
	  }
	}.values.toList
 
println(res)
 
}

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