Metrics selection

A metrics selector is a useful notation for controlling which metrics are returned in the measurement. When you request measurements -- either recent or historical -- you can limit which metrics get returned with the metricSelect parameter. Here are some examples, following by a more complete description of the notation:

Examples

Desired metrics	`metricSelect` value
The metrics that are returned by the API by default	absent or `default`
Every metric	`all`
Only metrics that start with “no2” (or similarly, only the category of NO2 pollutants)	`only no2*` or `only :no2`
Only metrics that are in the category of pollutants (thus leaving out environmentals like temperature and humidity)	`only :pollutant`
Only what a Node2 reports (no accessory module metrics)	`only :node2`
Defaults but not AQIs	`default - aqi`
Only Nowcasts	`only nowcast`

Metrics select language

The metrics selector creates a set, progressing left-to-right. The language is case-insensitive.

Start

A selection starts with

default or absent - set of default metrics
all - all the metrics for the given output frequency
none or only - the empty set

Add and remove

Then the language adds to or removes from the set. If not specified, you are adding. The selector only xxx starts with the empty set and then adds xxx.

Plus + and minus - toggle between add-to-set and remove-from-set. The selector none + no2* - *aqi starts empty, adds metrics that begin with "no2" and then remove metrics ending with "aqi".

Star matching

An asterisk * matches any text sequence.

* matches any text (so, all metrics)
temperature* matchings all text that starts with "temperature"
*rolling* matching any text with the word "rolling" in it. This would select all the rolling means.

Category matching

There are predefined categories of metrics that can be indicated with a leading colon :
For example, only :blackcarbon selects only the black carbon netrics