lowpass(<expression1>, <expression2>[, inner])
Returns only the points in
expression2 that are below
expression1 is often a constant. Specify
inner if you want an inner join.
|expression1||Threshold expression. Often a constant.|
|expression2||Expression that you want to filter.|
|inner||Results in an inner join.|
lowpass() filtering function plots a chart based on all reported data values that are lower than the specified threshold. The function discards data values that are greater than or equal to the threshold, resulting in gaps of missing data between the remaining points.
In the example chart above, solid orange lines are only present when the reported data values are lower than the threshold. In this example, the threshold is 140. The remaining reported data values display as dashed lines to indicate missing data.