Import Data to Lookup Table

R2026b

You can import data into lookup table from an Excel® spreadsheet using the readtable function or from the MATLAB® workspace.

Import Lookup Table Data from Excel Using readtable Function

To use the readtable function in a model to import data into a lookup table:

  1. Create or open an existing Excel spreadsheet, for example, an Excel spreadsheet that contains this data.

    Tip

    Instead of importing data into a lookup table, you can also copy and paste the contents of an Excel spreadsheet into a Lookup Table spreadsheet. See Copy and Paste Lookup Table Data from Excel.

     125
    -7235
    -4442

  2. Save the Excel file in a folder on the MATLAB path, for example, MySpreadsheet.xlsx.

  3. Create a model and add a 2-D Lookup Table block.

  4. In the model, select Model Settings > Model Properties.

  5. In the Model Properties dialog box, on the Callbacks tab, in the model callbacks list, select PostLoadFcn.

  6. To import the Excel spreadsheet data from Sheet1, use the MATLAB readtable function. This example code imports data for a 2-D lookup table. 

    % Import the data from Excel for a lookup table
data = readtable('MySpreadsheet','Sheet','Sheet1');
% Row indices for lookup table
breakpoints1 = data{2:end,1}';
% Column indices for lookup table
breakpoints2 = data{1,2:end};
% Output values for lookup table
table_data = data{2:end,2:end};

  7. Click OK.

After you save your changes, the next time you open the model, Simulink® invokes the callback and imports the data. To see the imported data, click the View diagnostics.

Import Lookup Table Data from MATLAB Workspace

These examples show how to import and export standard format and non-standard format data from the MATLAB workspace.

Import Standard Format Lookup Table Data

Suppose you specify a 3-D lookup table in your n-D Lookup Table block.

Create workspace variables to use as breakpoint and table data for the lookup table.

table3d_map = zeros(2,4,3);
table3d_map(:,:,1) = [     1     2     3     4;      5     6     7     8];
table3d_map(:,:,2) = [    11    12    13    14;     15    16    17    18];
table3d_map(:,:,3) = [   111   112   113   114;   115   116   117   118];
bp3d_z =[  0    10    20];
bp3d_x =[     0    10    20    30];
bp3d_y =[   400  6400];
Open the n-D Lookup Table block dialog box. On the Table and Breakpoints tab:

  • Table data: table3d_map

  • Breakpoints 1: bp3d_y

  • Breakpoints 2: bp3d_x

  • Breakpoints 3: bp3d_z

To open the Lookup Table Editor and show the data from the workspace variables, click Edit table and breakpoints.

Spreadsheet and 3-D mesh plot for a lookup table with breakpoints bp3d_x, bp3d_y, bp3d_z and output table3d_map.

Propagate Standard Format Lookup Table Data

When you make changes to your lookup table data, consider propagating the changes back to the MATLAB workspace variables the data was imported from using File > Update Block Data.

You can also use the Lookup Table Editor to edit the table data and breakpoint vectors of Simulink.LookupTable objects and the breakpoint vectors of Simulink.Breakpoint objects and propagate the changes back to the object.

Suppose you make a change to the lookup table variables imported from the MATLAB workspace variables in Import Standard Format Lookup Table Data. Change the value of the data in (1,1,1) from 1 to 33. To propagate this change back to table3d_map in the workspace, in the Lookup Table Editor toolstrip, click Apply.

Import Nonstandard Format Lookup Table Data

Suppose you specify a 3-D lookup table in your n-D Lookup Table block. Create workspace variables to use as breakpoint and table data for the lookup table. The variable for table data, table3d_map_custom, is a two-dimensional matrix.

table3d_map_custom = zeros(6,4);
table3d_map_custom = [     1     2     3     4;      5     6     7     8;
11      12     13      14;        15      16      17     18;
111   112    113    114;     115    116    117    118];
bp3d_z =[  0    10    20];
bp3d_x =[  0    10    20    30];
bp3d_y =[  400  6400];
Open the n-D Lookup Table block dialog box. On the Table and Breakpoints tab, enter these parameters. Transform table3d_map_custom into a three-dimensional matrix for the table data input using the reshape command.

  • Table data: reshape(table3d_map_custom,[2,4,3])

  • Breakpoints 1: bp3d_y

  • Breakpoints 2: bp3d_x

  • Breakpoints 3: bp3d_z

To open the Lookup Table Editor and show the data from the workspace variables, click Edit table and breakpoints.

Lookup Table Editor with spreadsheet, 3-D mesh plot, and Data Source panel showing workspace variables bp3d_x, bp3d_y, bp3d_z, and Table

In the Lookup Table Editor, change 1 to 33. The Lookup Table Editor records your changes by maintaining a copy of the table. To restore the variable values from the MATLAB workspace, in the Lookup Table Editor toolstrip, click Reload. To update the MATLAB workspace variables with the edited data, in the Lookup Table Editor toolstrip, click Apply. You cannot propagate the change to table3d_map_custom, the workspace variable that contains the nonstandard table data for the n-D Lookup Table block. To propagate the change, you must register a customization function that resides on the MATLAB search path. For details, see Propagate Nonstandard Format Lookup Table Data.

Propagate Nonstandard Format Lookup Table Data

Suppose your Simulink model from Import Nonstandard Format Lookup Table Data has a three-dimensional lookup table that gets its table data from the two-dimensional workspace variable table3d_map_custom. Update the lookup table in the Lookup Table Editor and propagate these changes back to table3d_map_custom using a customization function.

  1. Create a file named sl_customization.m with these contents.

    function sl_customization(cm)
cm.LookupTableEditorCustomizer.getTableConvertToCustomInfoFcnHandle{end+1} = ...
@myGetTableConvertInfoFcn;
end

    In this function:

    • The argument cm is the handle to a customization manager object.

    • The handle @myGetTableConvertInfoFcn is added to the list of function handles in the cell array for cm.LookupTableEditorCustomizer.getTableConvertToCustomInfoFcnHandle. You can use any alphanumeric name for the function whose handle you add to the cell array.

  2. In the same file, define the myGetTableConvertInfoFcn function.

    function blkInfo = myGetTableConvertInfoFcn(blk,tableStr)
        blkInfo.allowTableConvertLocal = true;
        blkInfo.tableWorkSpaceVarName = 'table3d_map_custom';
        blkInfo.tableConvertFcnHandle = @myConvertTableFcn;
end

    The myGetTableConvertInfoFcn function returns the blkInfo object containing three fields.

    • allowTableConvertLocal allows table data conversion for a block.

    • tableWorkSpaceVarName specifies the name of the workspace variable that has a nonstandard table format.

    • tableConvertFcnHandle specifies the handle for the conversion function.

    When allowTableConvertLocal is set to true, the table data for that block is converted to the nonstandard format of the workspace variable whose name matches tableWorkSpaceVarName. The conversion function corresponds to the handle that tableConvertFcnHandle specifies. You can use any alphanumeric name for the conversion function.

  3. In the same file, define the myConvertTableFcn function. This function converts a three-dimensional lookup table of size Rows * Columns * Height to a two-dimensional variable of size (Rows*Height) * Columns.

    % Converts 3-dimensional lookup table from Simulink format to
% nonstandard format used in workspace variable
function cMap = myConvertTableFcn(data)
    
% Determine the row and column number of the 3D table data
    mapDim = size(data);
    numCol = mapDim(2);
    numRow = mapDim(1)*mapDim(3);
    cMap = zeros(numRow, numCol);
   % Transform data back to a 2-dimensional matrix
    cMap = reshape(data,[numRow,numCol]);
end

  4. Put the sl_customization.m file on the MATLAB search path. You can have multiple files named sl_customization.m on the search path. For more details, see Behavior with Multiple Customization Functions.

  5. Refresh Simulink customizations at the MATLAB command prompt.

    sl_refresh_customizations

  6. Open the Lookup Table Editor for your lookup table block and select File > Update Block Data. Click Yes to overwrite the workspace variable table3d_map_custom.

  7. Check the value of table3d_map_custom in the base workspace.

    table3d_map_custom =

    33     2     3     4
     5     6     7     8
    11    12    13    14
    15    16    17    18
   111   112   113   114
   115   116   117   118

    The change in the Lookup Table Editor has propagated to the workspace variable.

Note

If you do not overwrite the workspace variable table3d_map_custom the software prompts you to replace it with numeric data. Click Yes to replace the expression in the Table data box with numeric data. Click No if you do not want your Lookup Table Editor changes for the table data to appear in the block dialog box.

Behavior with Multiple Customization Functions

At the start of a MATLAB session, Simulink loads each sl_customization.m customization file on the path and executes the sl_customization function. Executing each function establishes the customizations for that session.

When you select File > Update Block Data in the Lookup Table Editor, the editor checks the list of function handles in the cell array for cm.LookupTableEditorCustomizer.getTableConvertToCustomInfoFcnHandle. If the cell array contains one or more function handles, the allowTableConvertLocal property determines whether changes in the Lookup Table Editor can be propagated.

  • If the value is set to true, then the table data is converted to the nonstandard format in the workspace variable.

  • If the value is set to false, then table data is not converted to the nonstandard format in the workspace variable.

  • If the value is set to true and another customization function specifies it to be false, the Lookup Table Editor reports an error.

See Also

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