Handle data "gaps" when plotting

[trisyoungs]

At present we graph data by connecting all data points with a continuous line, which works fine for most occasions but can be misleading if a significant time gap occurs between two data points occurs for a quantity with a low variance. Then, is appears as if valid data was collected over the whole time range when this is not in fact the case.

For an example, see NIMROD run 69902 (cycle 19/4) and look at, for instance, the Coupled_Hydrogen parameter. There you'll see a data point at 2020-03-16T00:41:45 and then an 8.5 hour gap before the next point is collected (2020-03-16T10:16:55).

One option for resolving this is to only connect data points with a line when the time gap is less than a couple of minutes - the nature of the sample environment logging on the instruments mean that most information is collected every 30 seconds to 1 minute, so a gap longer than this could be suspicious. Of course, we would need an option somewhere (context menu perhaps?) to disable this if required.

Quite how this can be implemented effectively with a QXYSeries is another matter...