Managing Data in the App

Viewing Data Properties

You can get information about each data set in the System Identification app by right-clicking the corresponding data icon.

The Data/model Info dialog box opens. This dialog box describes the contents and the properties of the corresponding data set. It also displays any associated notes and the command-line equivalent of the operations you used to create this data.

    Tip   To view or modify properties for several data sets, keep this window open and right-click each data set in the System Identification app. The Data/model Info dialog box updates as you select each data set.

To displays the data properties in the MATLAB® Command Window, click Present.

Renaming Data and Changing Display Color

You can rename data and change its display color by double-clicking the data icon in the System Identification app.

The Data/model Info dialog box opens. This dialog box describes both the contents and the properties of the data. The object description area displays the syntax of the operations you used to create the data in the app.

The Data/model Info dialog box also lets you rename the data by entering a new name in the Data name field.

You can also specify a new display color using three RGB values in the Color field. Each value is between 0 to 1 and indicates the relative presence of red, green, and blue, respectively. For more information about specifying default data color, see Customizing the System Identification App.

    Tip   As an alternative to using three RGB values, you can enter any one of the following letters in single quotes:

    'y' 'r' 'b' 'c' 'g' 'm' 'k'

    These strings represent yellow, red, blue, cyan, green, magenta, and black, respectively.

Information About the Data

You can enter comments about the origin and state of the data in the Diary And Notes area. For example, you might want to include the experiment name, date, and the description of experimental conditions. When you estimate models from this data, these notes are associated with the models.

Clicking Present display portions of this information in the MATLAB Command Window.

Distinguishing Data Types

The background color of a data icon is color-coded, as follows:

  • White background represents time-domain data.

  • Blue background represents frequency-domain data.

  • Yellow background represents frequency-response data.

Colors Representing Type of Data

Organizing Data Icons

You can rearrange data icons in the System Identification app by dragging and dropping the icons to empty Data Board rectangles in the app.

    Note:   You cannot drag and drop a data icon into the model area on the right.

When you need additional space for organizing data or model icons, select Options > Extra model/data board in the System Identification app. This action opens an extra session window with blank rectangles for data and models. The new window is an extension of the current session and does not represent a new session.

    Tip   When you import or create data sets and there is insufficient space for the icons, an additional session window opens automatically.

You can drag and drop data between the main System Identification app and any extra session windows.

Type comments in the Notes field to describe the data sets. When you save a session, as described in Saving, Merging, and Closing Sessions, all additional windows and notes are also saved.

Deleting Data Sets

To delete data sets in the System Identification app, drag and drop the corresponding icon into Trash. You can also use the Delete key on your keyboard to move items to the Trash. Moving items to Trash does not permanently delete these items.

    Note:   You cannot delete a data set that is currently designated as Working Data or Validation Data. You must first specify a different data set in the System Identification app to be Working Data or Validation Data, as described in Specify Estimation and Validation Data in the App.

To restore a data set from Trash, drag its icon from Trash to the Data or Model Board in the System Identification app window. You can view the Trash contents by double-clicking the Trash icon.

    Note:   You must restore data to the Data Board; you cannot drag data icons to the Model Board.

To permanently delete all items in Trash, select Options > Empty trash.

Exiting a session empties the Trash automatically.

Exporting Data to the MATLAB Workspace

The data you create in the System Identification app is not available in the MATLAB workspace until you export the data set. Exporting to the MATLAB workspace is necessary when you need to perform an operation on the data that is only available at the command line.

To export a data set to the MATLAB workspace, do one of the following:

  • Drag and drop the corresponding icon to the To Workspace rectangle.

  • Right-click the icon to open the Data/model Info dialog box. Click Export.

When you export data to the MATLAB workspace, the resulting variables have the same name as in the System Identification app. For example, the following figure shows how to export the time-domain data object datad.

Exporting Data to the MATLAB Workspace

In this example, the MATLAB workspace contains a variable named data after export.

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