Filtering with Flux in InfluxDB

How does filtering works with Flux in InfluxDB?

The filter() function behaves similarly to the WHERE command in SQL.

from(bucket: "trial_bucket")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "service_org_duration")

• The fn parameter expects a predicate function, that is an anonymous function producing a boolean (true/false) output. The filtering will include rows for which fn returns true based on the expression.
• The r argument of the fn parameter stands for the rows.