...
Purpose and use of Transformation: | Can be used e.g. to filter out measurement values during periods where the measured system is not in a (quasi) steady state due to changes happening in the system. For example when a pump is switched on/off in a system of pipes, then the pressure in the pipes will fluctuate for some time until reaching an equilibrium value. If data analysis depends only on the equilibrium value, then this transformation can be used to filter out the fluctuating values just after a pump has been switched on/off in the system. |
|---|---|
Background and Exceptions: | Produces missing output values at times where there is not enough reliable or doubtful data available in the condition and/or expression variables to determine if there is a change or to determine the length of a time window. Any such missing output values are truncated from the start and end of the run period of the transformation, to avoid overwriting data from previous runs with overlapping run periods. |
variableDefinitions
It is possible to define embedded variables in this transformation. For inputVariable, conditionVariable and in the timeWindowLengthExpression both embedded variables and variables defined at the start of the transformations configuration file can be used. If an embedded variable and a variable defined at the start of the transformations configuration file have the same variableId, then the embedded variable will be used.
inputVariable
Input variable. This contains the times and values that are copied to the output variable if they are selected by this transformation.
conditionVariable
This condition variable is searched for changes during the run period of the transfomation. If for a given timeStep this variable has a value that is different from the value for the previous timeStep, then that counts as a change for the given timeStep. This triggers the creation of a selection time window that starts at the given timeStep.
timeWindowLengthExpression
Free format expression that is evaluated at the time of a change in the condition variable to determine the length of the time window (in seconds) for that change. For instance "X1 + X2". In the expression reference input variables or coefficients using their id, e.g. "X1 + a" where "X1" is the variableId of a variable and "a" is the id of a coefficient. Variables can be defined in this transformation or at the start of this transformations file. If a variable definition in this transformation has the same id as a variable definition at the start of this transformations file, then the variable definition in this transformation is used. Coefficients can be defined in a coefficientSet.
For examples of expressions and for all the options that can be used in a free format expression see UserSimple+Transformation.
CoefficientSets or CoefficientSetFunctions
TODO
selectionType
If this is select_inside_time_window, then all inputVariable values that are within at least one time window are copied to the outputVariable and all other inputVariable values are ignored. If this is select_outside_time_window then all inputVariable values that are within at least one time window are ignored and all other inputVariable values are copied to the outputVariable.
outputVariable
Output variable. Only the selected times and values are written in this outputVariable.
...