I am creating a bar graph in which the x-axis is composed of dates. The dates it receives are in strict_date_optional_time format. The graph automatically creates separate bars for each day. The user is able to choose the timeframe that the graph looks at, so I am trying to reduce the time frame of each period so that there is a bar for each hour for instance. I have been trying to use the xperiod attribute but have not been successful in implementing this. I am using a data frame to input data, so I am not using frames. If anybody has any advice on this matter, I would be very grateful.