Stack Table Variables

Combine values from multiple table variables into one table variable in the Live Editor

Since R2020a

Description

The Stack Table Variables task lets you interactively stack values from multiple table or timetable variables into one variable. The task automatically generates MATLAB^® code for your live script.

More

Related Functions

Stack Table Variables generates code that uses the stack function.

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Open the Task

To add the Stack Table Variables task to a live script in the MATLAB Editor:

• On the Live Editor tab, select Task > Stack Table Variables.

• In a code block in the script, type a relevant keyword, such as stack. Select Stack Table Variables from the suggested command completions.

Examples

Stack Table Variables Using Live Editor Task

This example shows how to stack variables by using the Stack Table Variables Live Editor task. It takes values from multiple variables in an input table, and combines them into one variable in an output table.

First, load a table that contains estimated influenza rates along the East Coast of the United States. The table has three variables with rates for the Northeast (NE), Mid-Atlantic (MidAtl), and Southeast (SE) regions. (These data come from the Google Flu Trends project, since discontinued.)

load fluByRegion
fluByRegion

fluByRegion=6×4 table
        Month          NE      MidAtl      SE  
    _____________    ______    ______    ______

     October-2005    1.1902    1.1865     1.273
    November-2005     1.361     1.412     1.582
    December-2005    1.5003    1.6043    1.8625
     January-2006    1.7772     1.883     1.954
    February-2006     2.135    2.1227    2.4803
       March-2006    2.2345     1.992    2.0203

Stack the flu rate data so that the flu rates from the NE, MidAtl, and SE variables are in one variable in the output table.

Add the Stack Table Variables task to your live script.

• To copy values from the Month variable to rows of the output table, select Constant from the drop-down list above it in the task.

• To combine the values from the NE, MidAtl, and SE variables by stacking them into one variable of the output, select Stack for each variable.

The name of the stacked variable in the output comes from combining the input variable names.

The task also stacks the names of the input variables into a new variable, named NE_MidAtl_SE_Indicator. In this example, the names of regions are the names of variables in the input table. Those names become data values in a new variable that indicates the regions for the flu rate data.

stackedTable=18×3 table
        Month        NE_MidAtl_SE_Indicator    NE_MidAtl_SE
    _____________    ______________________    ____________

     October-2005            NE                   1.1902   
     October-2005            MidAtl               1.1865   
     October-2005            SE                    1.273   
    November-2005            NE                    1.361   
    November-2005            MidAtl                1.412   
    November-2005            SE                    1.582   
    December-2005            NE                   1.5003   
    December-2005            MidAtl               1.6043   
    December-2005            SE                   1.8625   
     January-2006            NE                   1.7772   
     January-2006            MidAtl                1.883   
     January-2006            SE                    1.954   
    February-2006            NE                    2.135   
    February-2006            MidAtl               2.1227   
    February-2006            SE                   2.4803   
       March-2006            NE                   2.2345   
      ⋮

Give the variables of the output table more meaningful names. To rename table variables, use the renamevars function.

fluRate = renamevars(stackedTable, ...
                     ["NE_MidAtl_SE_Indicator","NE_MidAtl_SE"], ...
                     ["Region","Flu Rate"])

fluRate=18×3 table
        Month        Region    Flu Rate
    _____________    ______    ________

     October-2005    NE         1.1902 
     October-2005    MidAtl     1.1865 
     October-2005    SE          1.273 
    November-2005    NE          1.361 
    November-2005    MidAtl      1.412 
    November-2005    SE          1.582 
    December-2005    NE         1.5003 
    December-2005    MidAtl     1.6043 
    December-2005    SE         1.8625 
     January-2006    NE         1.7772 
     January-2006    MidAtl      1.883 
     January-2006    SE          1.954 
    February-2006    NE          2.135 
    February-2006    MidAtl     2.1227 
    February-2006    SE         2.4803 
       March-2006    NE         2.2345 
      ⋮

Related Examples

• Add Interactive Tasks to a Live Script

Parameters

Input table — Names of table or timetable

drop-down list items

Specify the name of the input table or timetable timetables from the lists of all the nonempty tables and timetables that are in the workspace.

Variables to stack — Actions for input variables

drop-down list items

Specify the action to take for each variable in the input table or timetable. When stacking variables, there are three possible actions:

• Constant — Copy the variable to the output table or timetable. Replicate its values where needed in rows of the output.

• Stack — Stack the values from the variable into one variable of the output. For example, if you choose to stack three variables, all their values go into one variable of the output.

• Discard — Exclude the variable and its values from the output.

Version History

Introduced in R2020a

R2022a: Live Editor task does not run automatically if inputs have more than 1 million elements

This Live Editor task does not run automatically if the inputs have more than 1 million elements. In previous releases, the task always ran automatically for inputs of any size. If the inputs have a large number of elements, then the code generated by this task can take a noticeable amount of time to run (more than a few seconds).

When a task does not run automatically, the Autorun indicator is disabled. You can either run the task manually when needed or choose to enable the task to run automatically.