ScopedLimit

Applies a limit to the sum of a group of records that share equal values in the columns specified by erode_by_columns. It is applied incrementally to groups of records that share same values in the columns specified by span_columns. Once the limit is applied, the result is proportionally allocated to all records in the group.

Structure

{
    "_schema": "ScopedLimit_1.0",
    "limit": 1000,
    "span_columns": ["Time"],
    "erode_by_columns": ["Time", "OccurrenceKey"],
    "currency":"GBP"
}

Parameters

Parameter Name	Required	Type	Description
limit	Yes	double	The limit value in currency units. Cannot be negative.
span_columns	No	string list	List of column names. Adjacent records with the same values in the provided columns will share the same eroding limit. Supported columns: OccurrenceKey, Time. If left empty, all records share the same limit.
erode_by_columns	No	string list	List of column names. Specifies the grouping of records the limit will apply to. Supported columns: OccurrenceKey, Time. Always implicitly contains the values in span_columns.
currency	No	string	The currency in which limit is defined.

Behaviour

Records which pass through scoped limit have their limit applied according to how they are grouped by span_columns and erode_by_columns. All adjacent records with matching values in the columns specified by span_columns are placed within a span group. All adjacent records with matching values in the columns specified by erode_by_columns within a span group are further placed in an erode group.

Within each erode group, the limit is applied to the sum of the records’ Value fields (sum) with the function new_sum = max(sum, -limit). This value is then proportionally allocated to the Value field of each record within the group with the function record.value = new_sum / sum. If sum is 0, then each records’ Value field is instead left unmodified. In either case, the limit is eroded with the function limit = max(limit + min(new_sum, 0), 0).

Within each span group, the value of the limit is reset to the original limit specified in the arguments.