Report line graph - Drawing nulls

I have a report with several line graphs. The dataset feeding the report is fetched with the function system.tag.queryTagHistory. Start time is midnight, end time is “now” if the report is generated current day, or it is +24hrs if the report is generated for a historical day.

I need to do some averaging of the data. I’ve set up averaging every 10 minutes.

This averaging causes the last row of the dataset to contain nulls.

This causes the line graph to draw the last value as 0 (not null).

I see two ways to handle this.

  1. Get the line graph to ignore null values.
  2. Remove nulls from the system.tag.queryTagHistory (how can this be done when using interval?).

One way is to set your Tag History binding to a custom property (dataset) and then use scripting to take the last row off of the dataset.