docs-v2/content/influxdb/v2.0/query-data/common-queries/compare-values.md

title	seotitle	description	influxdb/v2.0/tags	menu	weight
Comparing values from different buckets	Compare the last measurement to a mean stored in another bucket	Compare the value from the latest point to an average value stored in another bucket. This is useful when using the average value to calculate a threshold check.	queries	influxdb_2_0 name parent Compare values from different buckets Common queries	104

{{% note %}} This example uses NOAA water sample data. {{% /note %}}

This example compares the value from the latest point to an average value stored in another bucket. This is useful when using the average value to calculate a threshold check.

The following query:

• Uses [range()](/{{< latest "flux" >}}/stdlib/universe/range/) to define a time range.
• Gets the last value in the means bucket and compares it to the last value in the noaa bucket using [last()](/{{< latest "flux" >}}/stdlib/universe/last/).
• Uses [join()](/{{< latest "flux" >}}/stdlib/universe/join/) to combine the results
• Uses [map()](/{{< latest "flux" >}}/stdlib/universe/map/) to calculate the differences

means = from(bucket: "weekly_means")
  |> range(start: 2019-09-01T00:00:00Z)
  |> last()
  |> keep(columns: ["_value", "location"])

latest = from(bucket: "noaa")
  |> range(start: 2019-09-01T00:00:00Z)
  |> filter(fn: (r) => r._measurement == "average_temperature")
  |> last()
  |> keep(columns: ["_value", "location"])

join(tables: {mean: means, reading: latest}, on: ["location"])
  |> map(fn: (r) => ({r with deviation: r._value_reading - r._value_mean}))

Example results

location	_value_mean	_value_reading	deviation
coyote_creek	79.82710622710623	89	9.172893772893772
santa_monica	80.20451339915374	85	4.79548660084626