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Create and Edit Variables

Create Variables

The MATLAB® workspace consists of the variables you create and store in memory during a MATLAB session. You can create new variables in the workspace by running MATLAB code or using existing variables.

To create a new variable, enter the variable name in the Command Window, followed by an equal sign (=) and the value you want to assign to the variable. For example, if you run these statements, MATLAB adds the four variables x, A, I, and C to the workspace:

x = 5.71;
A = [1 2 3; 4 5 6; 7 8 9];
I = besseli(x,A);
C = {A A A};

Workspace browser showing all four variables

You do not have to declare variables before assigning values to them.

If you do not end the assignment statement with a semicolon (;), MATLAB displays the result in the Command Window. For example,

x = 5.71
x =
    5.7100

If you do not explicitly assign the output of a statement to a variable, MATLAB generally assigns the result to the reserved word ans. The value of ans changes with every statement that returns an output value that is not assigned to a variable. For example,

sin(1)
ans =
    0.8415

To view and edit variables, use the Workspace browser and Variables editor. (Some editing options are not available in MATLAB Online™.)

View Workspace Contents

To view a list of variables in your workspace, use the Workspace browser.

Workspace browser showing all four variables

To open the Workspace browser if it is not currently visible, do either of the following:

  • On the Home tab, in the Environment section, click Layout. Then, under Show, select Workspace.

  • Type workspace in the Command Window.

By default, the Workspace browser displays the base workspace. You also can view function workspaces if MATLAB is in debug mode. For more information, see Base and Function Workspaces.

To display additional columns such as size and range, on the Workspace browser title bar, click the Show Workspace Actions button , and then click Choose Columns. In MATLAB Online, to select which columns to display, right-click a column name in the Workspace panel and select or clear the desired column names.

You also can use the who command in the Command Window to view a list of variables. To list information about size and class, use the whos command. For example, if you have the variables x, A, and I in your workspace, you can run the who and whos commands to view your workspace contents:

who
Your variables are:

A  C  I  x
whos
  Name      Size            Bytes  Class     Attributes

  A         3x3                72  double
  C         1x3               528  cell
  I         3x3                72  double
  x         1x1                 8  double

View Variable Contents

You can view the contents of a variable in several ways:

  • Command Window — Type the variable name at the command prompt. For example:

    x
    x =
    5.7100

  • Variables editor — In the Workspace browser, double-click a variable name. The Variables editor opens for that variable.

    Variables editor showing C

    Some variables open a viewer or other tool appropriate for their type. For details, see the documentation for that data or object type.

    A Protected Property or Private Property icon next to a variable property in the Variables editor indicates that the property is protected or private, respectively.

    To change how the Variables editor displays variables, go to the View tab, and in the Format section, select a number display format. The display format does not affect how values are displayed in the Command Window or Workspace browser, or how the variables are saved.

    Note

    The maximum number of elements in a variable that you can open in the Variables editor depends on your operating system and the amount of physical memory installed on your system.

Edit Variable Contents

You can edit the contents of scalar (1-by-1) variables in the Workspace browser. To edit the contents, click the variable value to select it and then enter a new value.

To edit other variables, open them in the Variables editor. For example, suppose that you create a cell array, C, by running these commands in the Command Window:

A = magic(4);
C = {A A A};
In the Workspace browser, double-click the variable name C to open it in the Variables editor.

Variables editor showing C

To edit an element of a variable, double-click the element. The element opens in a new document within the Variables editor. For example, if you double-click element C{1,1} in the Variables editor, the contents of that cell open in a new tab. You can edit the value of a variable element by clicking the element and typing a new value. Press Enter or click another element to save the change.

Variables editor showing C{1,1}

To return to the parent cell array or structure of an element, go to the View tab and click the Go Up button.

Changes you make in the Variables editor are automatically saved in the workspace. Changes you make to variables via the Command Window or other operations automatically update the information for those variables in the Workspace browser and Variables editor.

Note

  • You cannot edit elements or subsets of multidimensional arrays in the Variables editor.

  • You cannot edit tall arrays in the Variables editor.

  • When editing strings in the Workspace browser or as part of a structure in the Variables editor, you must use double quotes to surround the string value.

Edit Table and Structure Array Variables

Tables (including timetables) and structure arrays support additional editing actions.

ActionProcedure
Modify column or row name

Double-click the name and enter the new text.

Variables editor, table view, with fourth column selected to be renamed

Reorder variables

Hover over the left side of a variable until a four-headed arrow appears. Then, click and drag the column to a new location.

Variables editor, table view, with third column prepared to be reordered

Modify units and description of variables

Click the arrow that appears to the right of a variable name. Then, enter new text in the Units and Description fields.

Variables editor, table view, with third column selected for modification of units and description of variables

Sort variable data

Click the arrow that appears to the right of a variable name and select Ascending or Descending.

Variables editor, table view, with third column selected for sorting

Note

The contents of a table are only visible and modifiable when the number of variables is fewer than 5000. When the number of variables equals or exceeds 5000, you can only view the table properties.

Changes made to certain variable types in the Variables editor also appear in the Command Window. For example, suppose you have a table T that contains three columns, A, B, and C. If you delete column A in the Variables editor, the line T(:,'A') = []; displays in the Command Window. To suppress code display in the Command Window, on the View tab, clear the Show MATLAB Code check box.

Resize or Reshape Variables

To modify the size, shape, and order of variable elements in the Variable editor, use one of these procedures.

ActionProcedure

Delete row, column, or variable elements

Right-click the desired row header, column header, or selected elements and select Delete Row or Delete Column.

Insert new row or column

 Right-click the desired row header, column header, or element and select Insert Row Above, Insert Row Below, Insert Column to the Left, or Insert Column to the Right. You can also add rows or columns simply by entering a value in an empty row or column. For example, to add a row and column to the array in C{1,1}, enter a value in element (5,5).

Cut variable elements

 Right-click the desired row header, column header, or selected elements and select Cut. The cut values move to the clipboard and are replaced by the default value for empty elements. For more information, see Empty Elements.

Copy variable elements

Right-click the desired row header, column header, or selected elements and select Copy.

Paste variable elements

Right-click the row header, column header, or element where you want the insertion to begin and select Paste.

Paste cells from Microsoft® Excel® spreadsheet

Right-click the element where you want the insertion to begin, and then select Paste Excel Data.

Empty Elements

Empty elements in variables are assigned default values. Default assignments are:

  • 0 for numeric arrays

  • [] for cell arrays and structure arrays

  • <undefined> for categorical variables

Copy, Rename, and Delete Variables

You can copy and paste, duplicate, rename, and delete variables within the Workspace browser.

ActionProcedure

Copy variable to and from clipboard

Select the variables, right-click, and then select Copy. Then, you can paste the names, for example, into the Command Window or an external application. Multiple variables are comma-separated.

Duplicate variable

Select the variables, right-click, and then select Duplicate. MATLAB creates a copy of the selected variables.

Rename a workspace variable

Right-click the variable name, and then select Rename. Type the new variable name and press Enter.

Delete all variables in workspace

On the Home tab, in the Variable section, click Clear Workspace.

You also can use the clear function in the Command Window.

Delete selected variables from workspace

Select the variables in the Workspace browser, right-click, and then select Delete.

You can also use the clear function in the Command Window. For example, to clear variables A and B, use the command clear A B.

To preserve specified variables, but delete others, use the clearvars function with the -except option. For example, to clear all variables except variable A, use the command clearvars -except A.

To create a new workspace variable from an existing variable, in the Variables editor, select an element, data range, row, or column in an array, and then in the Variable tab, select New from Selection.

You can change the character that delimits decimals in the data when you cut and paste values from the Variables editor into text files or other applications. You might do this, for instance, if you provide data to a locale that uses a character other than the period (.). To change the delimiter character, specify a Decimal separator for exporting numeric data via system clipboard in the Variables Preferences.

Navigate Variable Contents

When editing variables in the Variables editor, some variables can contain large amounts of data, making it difficult to navigate between elements. Use these keyboard shortcuts to move easily between variable elements in the Variables editor. You cannot modify these keyboard shortcuts.

Action

Keyboard Shortcut

Commit changes to element and move to next element.

Variables Preferences enable you to specify what the next element is. The default is to move down.

Enter

Move right.

Within a selection, Tab also moves from the last column in one row to the first column in the next row.

Tab

Move in opposite direction of Enter or Tab.

Shift+Enter or Shift+Tab

Move up m rows, where m is the number of visible rows.

Page Up

Move down m rows, where m is the number of visible rows.

Page Down

Move to column 1.

Home

Move to row 1, column 1.

Ctrl+Home

Edit current element, positioning cursor at the end of the element.

F2 (Ctrl+U on Apple Macintosh platforms)

See Also

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