Extracting event frames¶
Since the data in the PI archive is compressed by default, the time interval
between consecutive values is typically irregular. To get values at regular
intervals the interpolated_values method is used. This is available on both
PIPoint
, and PIAFAttribute
objects.
For simplicity this tutorial only uses PIPoint
objects, see the
tutorial on PI AF to find how to access
PIAFAttribute
objects.
Basic usage¶
The basic example takes the first PIPoint
that is returned by the
server and gets the data for the last hour at 5 minute intervals,
by specifying the start_time, end_time, and interval arguments to
PIPoint.interpolated_values
:
import PIconnect as PI
with PI.PIServer() as server:
points = server.search('*')[0]
data = points.interpolated_values('*-1h', '*', '5m')
print(data)
Filtering values¶
To filter the interpolated values the same filter_expression syntax as for Filtering values can be used.