How to output information grouped by each value in rails?

########Model####################################
# pref.rb (province)
class Pref<ApplicationRecord
  has_many —Stations
end

# station.rb (station name)
class Station <ApplicationRecord
  belongs_to —pref
  belongs_to:line, foreign_key: 'line_id', primary_key: 'line_id'
end

# line.rb (route name)
class Line <ApplicationRecord
  has_many:stations, class_name: 'Station', foreign_key: 'line_id', primary_key: 'line_id'
end


######### Controller ########
#stations_controller.rb
class StationsController <ApplicationController
  def index
    @pref_name =Station.find_by (pref_id:params[:area_id])
    @stations=Station.where(pref_id:params[:area_id])
  end

  def show
  end

end


#########View ########
#stations/index.html.erb

<div class="container">
  <div class="row">
    <div class="col-md-12">
      <h1><%=@pref_name.pref.name%>|<%[email protected]%>Station|Stations #index</h1>
      <p>Find me in app/views/stations/index.html.erb</p>

          <%@stations.each do | station | %>
            <div class="panel panel-default">
                  <div class="panel-heading">%=station.line.line_name%>/div>
                <ul class="list-group">
                      <lic class="list-group-item">%=station.station_name%>/li>
                </ul>
            </div>
          <%end%>
    </div>
  </div>
</div>