Hi,
I am trying to set up a Custom Calculation to check if a variable is under many conditions, but I got stuck in a problem. The two limits (max and min) only get new data points in the data base when we change recipes. I tried to use .ffill() to fill the data base with the older values, but it did not work. I still get NaN results for the time I dont have values.
Hi,
The .ffill() method only works if there are existing values in the interval you are fetching. The index_interval changes every time the script runs, since it defines the time window where new values should be calculated.
Backward indexing (when saving a new tag): the index_interval usually spans 30 days.
Forward indexing (when keeping a saved tag up to date): the index_interval is much shorter anywhere from a few minutes to a few hours.
If your limit tags (min and max) don’t have any data inside that index_interval, then .ffill() will return NaN, because there’s no previous value available in the requested range.
To solve this fetch a slightly larger time interval that extends before and after your calculation window. The size of this buffer should depend on how often your limit tags update.
Example: if your tags only update once a month, fetch at least one month of extra data in addition to the calculation interval.
Let me know if this solves your issue!
Kind regards
Frederik
No account yet? Create an account
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.