def barchart_data():
    if request.method == 'POST':

        picked_idx = [request.json['picked_sn'] - 1]

        selected_idx = request.json['selected_sn']
        selected_idx = [num - 1 for num in selected_idx]

        barchart_data = calc_barchart_data(picked_idx, selected_idx)
        return barchart_data