how to use .map{|x| x[1]} with group_by_period in rails

I want to show data for the past 14 days where requests have occurred which is showing on map

 @maintenance_count = Maintenance.where(property_id: property_ids)
.where("created_at >= ?", start_date)
.group_by_period(params[:day_month], :created_at, series: true, format: date_format, 
 last: params[:duration].to_i)
.count.map{|x| x[1]}

this is taking params from URL i assigned like this

 a.dropdown-item  href="?day_month=day&duration=14" 14 Days
a.dropdown-item  href="?day_month=week&duration=8" 8 weeks
a.dropdown-item  href="?day_month=month&duration=12" 12 months
 a.dropdown-item  href="?day_month=year&duration=2" 2 years

i want to show for past 14 days when params are empty but i don't know how this array working with map

labels: @maintaince_ending_labels,
              datasets: [
                {                    
                    data: @maintenance_count
                },
              ]

 if params[:day_month] == "day"
  start_date = (Date.today - params[:duration].to_i.day).beginning_of_day
  date_format = '%a %d'