Flow to stock: flow_to_stock

Syntax

flow_to_stock ( op )

Input parameters

op	the operand

Examples of valid syntaxes

flow_to_stock ( ds_1 )

Semantics for scalar operations

This operator does not perform scalar operations.

Input parameters type

op

dataset { identifier < time > _ , identifier _* , measure<number> _+ }

Result type

result

dataset { identifier < time > _ , identifier _* , measure<number> _+ }

Additional Constraints

The operand dataset has an Identifier of type time, date or time_period and may have other Identifiers.

Behavior

The statistical data that describe the “state” of a phenomenon on a given moment (e.g. resident population on a given moment) are often referred to as “stock data”.

On the contrary, the statistical data that describe “events” which can happen continuously (e.g. changes in the resident population, such as births, deaths, immigration, emigration), are often referred to as “flow data”.

This operator takes in input a Data Set which are interpreted as flows and calculates the change of the corresponding stock since the beginning of each time series by summing the relevant flows. In other words, the operator perform the cumulative sum from the first Data Point of each time series to each other following Data Point of the same time series.

The flow_to_stock operator can be applied only on Data Sets of time series and returns a Data Set of time series.

The result Data Set has the same Identifier, Measure and Attribute Components as the operand Data Set and contains the same time series as the operand, because the time series Identifiers (all the Identifiers except the reference time Identifier) are not changed.

As mentioned in the section “Behaviour of the Time Operators”, the operator is assumed to know which is the time Identifier as well as the period of each time series.