How to include a wide table's VariableDescriptions as an additiolnal column when stacking the table?

Question

Simon 2023-3-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1932360-how-to-include-a-wide-table-s-variabledescriptions-as-an-additiolnal-column-when-stacking-the-table

编辑： Simon 2023-4-23

I would like to make a wide table's VariableDescriptions as an additional column when I stack the table. I have written some codes to do it. They work (in a dirty manner). Is there a better way?

T = cell2table({'A', 2, 3, 3; 'B', 5, 5, 7}, "VariableNames", {'AB', 'x', 'y', 'z'});
% variable descriptions
T.Properties.VariableDescriptions =  {'AB', 'xdes', 'ydes', 'zdes'};
S = stack(T, 2:4, "IndexVariableName",'xyz', 'NewDataVariableName','value')
S = 6×3 table
     AB      xyz    value
    _____    ___    _____

    {'A'}     x       2  
    {'A'}     y       3  
    {'A'}     z       3  
    {'B'}     x       5  
    {'B'}     y       5  
    {'B'}     z       7  
% duplicate the table, using the variable descriptions as new variable names.
T2 = T;
T2.Properties.VariableNames = T.Properties.VariableDescriptions;
% stack the second table
S2 = stack(T2, 2:4, "IndexVariableName",'xyzdes', 'NewDataVariableName','value');
% add the descriptions as a new column to the first table
S.xyzdes = S2.xyzdes;
S = movevars(S, "xyzdes", "After", "xyz")
S = 6×4 table
     AB      xyz    xyzdes    value
    _____    ___    ______    _____

    {'A'}     x      xdes       2  
    {'A'}     y      ydes       3  
    {'A'}     z      zdes       3  
    {'B'}     x      xdes       5  
    {'B'}     y      ydes       5  
    {'B'}     z      zdes       7  

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Answer 1

Divyanshu 2023-4-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1932360-how-to-include-a-wide-table-s-variabledescriptions-as-an-additiolnal-column-when-stacking-the-table#answer_1218043

在 MATLAB Online 中打开

The key concept used here is of a Map where variable names of the table are keys, and their values are the variable descriptions. For simplicity I have assumed names to be in ‘names’ and descriptions in ‘desc’.

Here is a demo script of doing the same where a new column is added at the end of the stacked table:

names = ["x" "y" "z"];
desc = ["xD" "yD" "zD"];
M = containers.Map(names,desc);
col2 = S(:,2);
len = height(col2);
colN = []
for i=1:len
    colN = [colN;string(M(string(col2{i,:})))];
end
colN = table(colN)
S = [S colN]

In the above script S is the stacked table that was created by your code.

The vector ‘colN’ is the new column vector which holds the descriptions.

Please refer to the following documentation to get more information about Maps:

Object that maps unique keys to values - MATLAB (mathworks.com)

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Simon 2023-4-23

编辑：Simon 2023-4-23

Thanks for the answer. I didn't know 'containers.Map' before. But Matlab has just created 'dictionary', which serves similar purpose and can take more flexible data type. Anyway, key-value mapping is a great idea in solving my problem.

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