first

Return the value of the specified field in the first point that contains it.

put|reduce first(field)

Parameter	Description	Required?
field	The field to return	Yes

Example

This example uses the batch processor.

// On historical data, you can apply reducer to get a single computation,
// or batch your historical data by time, then reduce per batch period.

sub historical_points() {
  emit -from :0: -limit 10 | put cnt = count(), value = Math.random()
}
historical_points 
| reduce first(cnt), first_val = first(value), last(cnt), last_val = last(value)
| view table -title "First and last historical points"
;
historical_points 
| batch 5 
| reduce first(cnt), last(cnt) 
| view table
    -update "append" 
    -title "First and last points per 5-second batch, historical"
;

// On live streaming data, you must batch by time, then reduce per batch period.

sub live_points() {
  emit -limit 10 
  | put cnt = count(), value = Math.random()
}
live_points 
| batch 3 
| reduce first(cnt), last(cnt) 
| view table
    -update "append" 
    -title "First and last points per 3-second batch, live"
;