func.lag
This analytic function lets you query more than one row in a table at a time without having to join the table to itself
Syntax
func.lag(field, 1).over(partition_by=field, order_by=field)
Examples
This is an example of using the lag() capability to calculate the time interval in time series data where each event is on a distinct row.
This assumes you have a table of time series data that looks like this:
| location | employee | timestamp |
|---|---|---|
| Building A | John Doe | 2022-01-05 15:34:31 |
| Building A | John Doe | 2022-01-05 15:44:31 |
| Building A | John Doe | 2022-01-05 15:46:41 |
table.timestamp - func.lag(table.timestamp, 1).over(partition_by=[table.location, table.employee], order_by=table.timestamp)
Adding the expression above to an Interval column called delta would result in an output table like this:
| location | employee | timestamp | delta |
|---|---|---|---|
| Building A | John Doe | 2022-01-05 15:34:31 | null |
| Building A | John Doe | 2022-01-05 15:44:31 | 00:10:00 |
| Building A | John Doe | 2022-01-05 15:46:41 | 00:02:10 |
Last modified April 06, 2022 at 10:08 AM EST: Initial Documentation Commit (371ae8f)