def print_elapsed_time(ref_datetime, description):
    print('{} (took {}ms)'.format(description, floor((datetime.now()-ref_datetime).microseconds/1000)))
    return datetime.now()

def simpleview(request):
    time_marker = datetime.now()
    device_name = request.GET['device']
    device = Datalogger.objects.get(device_name=device_name)

    sensors = Sensor.objects.filter(datalogger=device).order_by('pk')
    sensor_count = len(sensors)  # should be no worse than count() since already-evaluated and cached.  todo: confirm

    #assign each sensor an index for the tuples (zero is used for time/x-axis)
    sensor_indices = {}
    for idx, sensor in enumerate(sensors, start=1):
        sensor_indices.update({sensor.sensor_name:idx})

    time_marker = print_elapsed_time(time_marker, 'basic gets')

    # process data into timestamp-grouped tuples accessible by sensor-index ([0] is timestamp)
    raw_data = SensorDatum.objects.filter(sensor__datalogger__device_name=device_name).order_by('timestamp', 'sensor')
    data = []
    data_idx = 0

    time_marker = print_elapsed_time(time_marker, 'queried data')

    while data_idx < len(raw_data):
        row_list = [raw_data[data_idx].timestamp]
        row_list.extend([None]*sensor_count)
        row_idx = 1

        while data_idx < len(raw_data) and raw_data[data_idx].timestamp == row_list[0]:
            row_idx = sensor_indices.get(raw_data[data_idx].sensor.sensor_name)
            row_list[row_idx] = raw_data[data_idx].value
            data_idx += 1
        data.append(tuple(row_list))

    time_marker = print_elapsed_time(time_marker, 'split data by sensor')

    column_labels = ['Time']
    column_types = ["datetime"]
    for sensor in sensors:
        column_labels.append(sensor.sensor_name)
        column_types.append("number")

    time_marker = print_elapsed_time(time_marker, 'prepared column labels/types')

    gchart_json = prepare_data_for_gchart(column_labels, column_types, data)


    time_marker = print_elapsed_time(time_marker, 'prepared json')


    context = {
        'device': device_name,
        'sensor_count': sensor_count,
        'sensor_indices': sensor_indices,
        'gchart_json': gchart_json,
    }

    time_marker = print_elapsed_time(time_marker, 'created context')

    return render(request, 'pulogger/simpleTimeSeriesView.html', context)