# IBM Visualization Data Explorer User's Reference

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### Sequencer

Category

Special

Function

Generates a sequence of integers.

Syntax

The sequencer is available in script mode and in the user interface. However, it can be data driven only in the user interface (see Chapter 10. "Data Explorer Scripting Language" in IBM Visualization Data Explorer User's Guide, and the example later in this section.)

Inputs

Name | Type | Default | Description
--- | --- | --- | ---
`min` | integer | 1 | minimum of integer sequence
`max` | integer | 100 | maximum of integer sequence
`delta` | integer | 1 | numerical interval between successive integers in the sequence

Outputs

Name | Type | Description
--- | --- | ---
`frame` | integer | frame number

Functional Details

This module allows a user to "animate" a visualization. Through inputs to the module (outputs from other tools or values set in its configuration dialog box) the interactor can be "data driven."

If the interactor is not data-driven, its attributes are taken from its `Frame Control` dialog box (accessed from the `...` button).

The configuration dialog box for Sequencer can be accessed by selecting the Sequencer icon in the VPE and then choosing `Configuration` in the `Edit` menu.

`min` and `max` | specify the minimum and maximum integer values (frame numbers) for an "animation" sequence. By default, `min` = 1 and `max` = 100.
`delta` | specifies the increment between integers in the output sequence. If `min` and `max` are equal, `delta` is ignored. By default, `delta` = 1.

Note: If `min` is specified, and either `min` or `max` change, the output value (`frame`) is set to the new `min` value and the Start and Stop values in the Frame Control dialog box are set to the new minimum and maximum, respectively.

However, if `min` is not specified and `max` is and then changes on the next execution, the output frame value becomes the current Start value as set in the Frame Control dialog box.

Script Language Example

The following example uses the Sequencer in script mode to display a series of isosurfaces. The input to the macro `do_each_frame` is the frame number, which is converted into an isosurface value by multiplying it by 0.05. The initialization values are set by `@startframe, @endframe, and @nextframe`. The sequence command invokes the macro for each step of the sequence. Finally, the play command starts the Sequencer running. For more information about using the sequencer in script mode, see Chapter 10. "Data Explorer Scripting Language" in IBM Visualization Data Explorer User's Guide.

    macro do_each_frame(frame)
    {
       isovalue = frame*.05;
       isosurface = Isosurface(data,isovalue);
       Display(isosurface,camera);
    }
    data = Import("/usr/lpp/dx/samples/data/cloudwater");
    camera = AutoCamera(data);
    @startframe = 1;
    @endframe = 5;
    @nextframe = @startframe;
    sequence do_each_frame(@frame);
    play;

Example Visual Programs

Many of the example visual programs use a sequencer, including:

    ContoursAndCaption.net
    GeneralImport1.net
    MovingCamera.net

The following example visual program uses a data-driven Sequencer:

    Imide_potential.net

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