Group By

Aggregates groups of rows into a single row

Processing

The step calculates group fields for each row, and aggregates values per group.

Mode

The mode to use:

• one aggregate row per group generates one summary row per group
• keep all rows, add rolling aggregate to each row passes through all input rows immediately, attaches partial aggregate
• keep all rows, add complete aggregate to each row caches each group’s input rows and outputs them once the group is complete - attaches full group aggregate value to each row

Group By

Defines the grouping of rows.

Evaluated for each input row

Type

Data type of the grouping field. Values are implicitly cast to this type.

Name

Name of the grouping field.

Value

Value of the grouping field.

Settings

Aggregate

Defines aggregated fields for each group.

Type

Type of the field. Final aggregated value is cast to this type.

Name

Name of the field.

Aggregation

Evaluated once when step initializes
You can specify an aggregator in the following ways:

• Use one of the aggregators available in the morph context menu.
• Supply a function (a, x) -> any that receives the current aggregate value as a, and the subject to aggregate as x. The function returns the new aggregate value. When invoked for the first time per group, a is nil.
• Supply a dict with the following keys:
  • init (optional) initial aggregation state. nil is implied if omitted.
  • acc aggregation function (a, x) -> any that receives the current aggregation state a and the subject to aggregate as x and returns the new aggregation state.
  • out (optional) function (a) -> any that receives the current aggregation state and returns the aggregation value to place in the aggregation field. (a) -> a is implied if omitted.

Subject

Evaluated for each input row
The subject to aggregate.

Results