Hi. This is a common issue in aerospace. There are two solutions here, depending on how reliable your data source is. 1) If you are entirely sure that your datasource emits at 10ms intervals, then you can safely ASSUME that each record is 10ms apart. But that is an assumption: you should justify it. Assuming that it's justified, then, as others have suggested, there is likely, for any PHYSICAL transducer, to be a valid range of possible outputs, and a "NULL" (aerospace equivalent terminology: No Computed Data, or NCD) value could be chosen to be a float outside this range. Alternatively, you could use HUGE_VAL or -HUGE_VAL (IEEE + or - infinity encodings) or NAN, depending on how HDF handles this.
2) If you have any doubts whatsoever about the regularity in time of your data source, then you should store a timestamp with each record: then gaps are obvious, as previously pointed out, by the delta in the timestamps, which might be due to non-availability of sensor data, or irregular scheduling of your acquisition code (assuming that you are polling the device). Finally, regarding file size, it is often useful to record only CHANGES (how you define a significant change is up to you) as timestamped events. This gives you, automatically, a very small number of records if your data remains static over a long period, but is of limited use if your source is "noisy" (i.e. constantly changing). -- View this message in context: http://hdf-forum.184993.n3.nabble.com/How-to-write-empty-or-missing-values-in-a-dataset-tp1766106p1785322.html Sent from the hdf-forum mailing list archive at Nabble.com. _______________________________________________ Hdf-forum is for HDF software users discussion. [email protected] http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
