Deactivate the automatic interpolation of data in DIAdem

Question

Bonjour!
Nous sommes intéressés à désactiver l'interpolation que DIAdem fait automatiquement des données manquantes d'une base de données MySQL. En fait nous voudrions fixer une valeur de plage manquante à partir de laquelle l'interpolation des données ne se ferait  plus.  Par exemple: si les données sont absentes sur moins de 30 minutes, interpoler, si les données sont absentes sur plus de 30 minutes, ne pas interpoler. Est-ce possible de donner ce paramètre à DIAdem? Merci!

Answer 1

Hi frpic76,
Let me repeat back to you in English what I think you're asking and then give you a few thoughts-- unfortunately my ability to write French is even worse than my ability to read it.  It sounds like you want to apply interpolation to your aquired data only when the region of missing data is within a certain minimum amount, but if you have data missing for much longer intervals (say, between tests run in different months) you do not want any interpolation.  This sounds reasonable enough.  You also mention that you are storing the data in a MySQL data base, so I'm surprised that you can not query out only the data you want (which presumably all falls into the category of needing interpolation).
I'm also unclear what you mean by interpolation.  Normally I would understand that to mean imposing an expected timebase on data that was acquired at larger time intervals or at irregular time intervals, wherby you determine the interpolated Y values based on weighted linear extrapolation from the closest adjacent acquired values.  But DIAdem does not do this automatically, as you seem to suggest.  What DIAdem does do is plot all isolated XY cartesian pairs on a VIEW or REPORT graph, but here DIAdem just connects each individual graphed data point to the next data point with a straight line-- the intervening values are neither calculated nor regular.  Still, if this is what you mean, then there are two easy solutions.  First, you can insert a NoValue after the end of the values from the first data set and before the values of the second data set-- graphs in VIEW and REPORT will not plot a line to a NoValue.  Alternatively, you could change your SQL query to only read into DIAdem the data from one measurement at a time.
Feel free to ask follow-up questions in English or French,
Brad Turpin
DIAdem Product Support Engineer
National Instruments