VI Calc Process Object

The Visual Integrator (VI) Calc process object defines new columns or updates existing columns with the results of calculations and passes the results into the data flow.

VI Calc Process Object icon

A calculation string provides the formula for the column. This formula is defined using Integrator calculation syntax. You can have multiple calculations in one Calc object.

These calculation strings can refer to each other in the same Calc object. However, references to a calculated column by another calculation use the original value, not the new one if the referenced calculation has the Update attribute set to True. Use a separate Calc object for access to both the original and updated values.

The Calc process object has Closedfive panes where you set attributes.

VI Calc All Panes

You set attributes for the Calc object in the Closedobject attributes pane.

VI Calc Attributes Pane

Attribute Description
Input

Defines the object from which the data flow arrives. Use one of the following methods to attach the Calc object to an input data flow object:

  • Right-click the input data flow object, and click New Object after this > Process > Calc.

  • Place a Calc object on the task flow, and click its Input attribute's browse button. Move the pointer to the task flow, and note that a dotted-line connector is attached to the Calc object. Attach this connector to the input data flow object.

    NOTE: The Calc object's Input attribute is populated with the name of the input data flow object.

Calc_List_Input

Specifies a separate input flow object that is used to define new calculated columns. You can have the calculation definitions read from files or define them in a List input object. For more information, see VI List Input Object.

By using the Calc_List_Input attribute, you can share calculation definitions among VI scripts and allow users to add calculated columns without the need to edit the VI script.

Required and optional columns for files referenced by the Calc_List_Input are:

  • name (required)—Specifies the names for the calculated columns
  • value (required)—Specifies the calculation definition string
  • persistent (optional)—Sets the Persist attribute value to true
  • initial_value (optional)—Sets the initial value
  • update (optional)—Sets the Update attribute value to true

To populate the Calc_List_Input attribute:

  1. Create an input object that contains the calculation definitions within it. Use a Filein or List input object.
  2. Click the browse button for the Calc_List_Input attribute in the Calc object.
  3. Move the pointer to the task flow, and note that a dotted-line connector is attached to the Calc object.
  4. Attach the dotted-line connector to the input data flow object created in step one.

Each object has an area where you can enter comments.

It is a DI best practice to enter a note for every object in a VI script. You can set a VI preference to give a warning for each object without a note. For more information, see Visual Integrator Preferences.

ClosedCalc object with comments

VI Calc Object Comments

The Closeddefined calculations allow you to create new data columns in the data flow.

VI Calc Defined Calcs Samples

The general form of these calculations is: function(arg, arg, ...), where the arguments can be column names, variables (parameters), or constants.

There are two methods for completing calculation definitions: type the string directly into the definition panel, or pick functions and columns from the column grid and functions panel.

  1. Click in a row in the Name column, and specify a name for the calculation.
  2. Click the Definition panel.
  3. Enter the calculation expression in the form of: function(arg, arg, ...).
  4. For each calculation definition, set the Initial Value and the Persist and Update flags as required.

NOTE:

  • You can use the Ctrl+Space shortcut as you type in the definition to get a Closedpop-up pick list of functions to choose from. Enter the first few characters of the function, select the desired function with the arrow keys or mouse pointer, and then press Enter or double-click the function.
  • ClosedColor coding in the Definition pane visually displays the command syntax elements: blue for function names, black for operators, and green for column names.
  • As you enter elements in the Definition pane, tooltips appear that give a brief description of syntax. You can turn these tooltips off in the VI preferences. For more information, see Visual Integrator Preferences.

  1. Click in a row in the Name column, and specify a name for the calculation.

  2. Double-click a function from the Functions pane. For example; concat(,).

    That function is added to the calculation definition in the ClosedDefinition pane.

    VI Calc Object Defining 01

  3. With the focus still in place within the concat(,) function, double-click an input column from the Input Column column in the column grid. For example, Customer Name.

    That column is added to the ClosedDefinition pane.

    VI Calc Definition - add customer

  4. Enter an open bracket in quotes followed by a comma ("[",).

  5. Double-click the next column you want to concatenate. For example, Customer ID.

  6. Enter a comma and closed bracket in quotes (, "]") to complete the calculation.

    The second column is added to the ClosedDefinition pane.

    VI Calc Definition - add cust-id

    NOTE: The Value column updates automatically to reflect each change made in the definition pane. In this example, after Customer ID is added to the definition, it appears in the Value column.

TIP: To delete multiple rows, you can multi-select calc rows by holding CTRL and clicking with the right mouse button; select the Delete line in the context menu after the last selection.

The ClosedCalc column grid displays the input data flow.

VI Calc Object Column Grid

Attribute Description
Input Column

Displays the name of each input column. This attribute is read-only.

Double-click a column to place that column into the active calculation definition at the cursor location.
Source Object

Displays the name and object type of the source object. Double-click the Source Object for a column to change the task flow focus to that object.

You can choose functions to insert in the calculation definition from the ClosedCalc Functions pane.

VI Calc Object functions

The functions are listed in logical, string, and miscellaneous categories by default.

NOTE: To list functions alphabetically without the categories, you can change a preference. See Visual Integrator Preferences, and set the Sort calc functions by category preference to False.

Double-click the function to enter it into the Definition pane.

See also: