Determines whether this aggregation function is enabled or disabled.

Sets the aggregation function. All values from the linked `target`, corresponding to the same value in the `groups` array, are collected and reduced by this function. *count* is simply the number of values in the `groups` array, so does not even require the linked array to exist. *first* (*last*) is just the first (last) linked value. Invalid values are ignored, so for example in *avg* they do not contribute to either the numerator or the denominator. Any data type (numeric, date, category) may be aggregated with any function, even though in certain cases it is unlikely to make sense, for example a sum of dates or average of categories. *median* will return the average of the two central values if there is an even count. *mode* will return the first value to reach the maximum count, in case of a tie. *change* will return the difference between the first and last linked values. *range* will return the difference between the min and max linked values.

*stddev* supports two formula variants: *sample* (normalize by N-1) and *population* (normalize by N).

A reference to the data array in the parent trace to aggregate. To aggregate by nested variables, use *.* to access them. For example, set `groups` to *marker.color* to aggregate over the marker color array. The referenced array must already exist, unless `func` is *count*, and each array may only be referenced once.

Determines whether this aggregate transform is enabled or disabled.

Sets the grouping target to which the aggregation is applied. Data points with matching group values will be coalesced into one point, using the supplied aggregation functions to reduce data in other data arrays. If a string, `groups` is assumed to be a reference to a data array in the parent trace object. To aggregate by nested variables, use *.* to access them. For example, set `groups` to *marker.color* to aggregate about the marker color array. If an array, `groups` is itself the data array by which we aggregate.