Limitations for table variable name

Hello, dear community!

I try to name table variable with non-Latin character, for example Cyrillic:

>> a = table(zq, 'VariableNames', cellstr('я'));
Error using matlab.internal.tableUtils.makeValidName (line 36)

'я' is not a valid variable name.

Error in setVarNames (line 48)
[newnames,wasMadeValid] = matlab.internal.tableUtils.makeValidName(newnames,exceptionMode); % will warn if mods are made

Error in table (line 305)
            t = setVarNames(t,vnames); % error if invalid, duplicate, or empty

If I do the same, but with variable named using Latin characters, then everything works fine. What could cause this error? Is this normal behavior?

Thank you.

Answer 1

[Walter Roberson]

Normal. The names have the same restrictions as matlab variable names. Latin letter to start, continue with digits or underscore or Latin letters

[Andrey Kazak]

Thank you. Is this possible to avoid naming columns in a MATLAB table, so it would be default A, B, C, D, ...?

[Walter Roberson]

If you do not assign VariableName yourself, the default is 'Var1', 'Var2', 'Var3', and so on. You can assign 'A' 'B' and so on if you want.

[Andrey Kazak]

That is right. What I want is to export my table to XLSX where first row contains headers with non-Latin (Cyrillic) characters. I see now that this could require some pretty sophisticated workaround.

[Walter Roberson]

It appears that you could do it in two phases. One phase would have you xlswrite() a cell array that was the headers you want. The second phase would be to writetable() with WriteVariables set to 0 and a Range set to skip over the first row.

[Andrey Kazak]

Thank you, Walter. I made this in the following way:

1. Created a matrix with the data and added top row of NaN
2. xlswrite the matrix to a new XLSX file
3. Created cell array of text headers, which is basically a row of text cells
4. xlswrite the cell array to the same XLSX file

In the result I get with excel spreadsheet with header line and data.

In summary it seems not very convenient that MATLAB table column names are limited to MATLAB variable naming convention.

[Walter Roberson]

If using xlswrite is acceptable, then use num2cell() to convert the numeric matrix to a cell array, add the headers to the top of that, and xlswrite() the whole thing out.

Answer 2

[Vy Le]

Hi, why I write it and they said 'inifity norm of number c' is not a valid table variable name

Thank you.

names = {'inifity norm of condition number c','infinity norm of the residual r1'};

table(c,r1,'VariableNames',names)

[Steven Lord]

Prior to release R2019b table variable names were required to be valid MATLAB identifiers. In particular, that meant no spaces. That limitation was removed in release R2019b.

v = (1:5).';
A = table(v, v.^2, v.^3, 'VariableNames', ["v", "v squared", "v^3"])

A = 5x3 table
    v    v squared    v^3
    _    _________    ___

    1        1          1
    2        4          8
    3        9         27
    4       16         64
    5       25        125