"T.Properties.VariableNames" will not allow me to include parentheses () or brackets [ ] in my column heading

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James Long 2017-4-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/335829-t-properties-variablenames-will-not-allow-me-to-include-parentheses-or-brackets-in-my-colum

评论： James Long 2017-4-18

"T.Properties.VariableUnits" and "T.Properties.VariableDescriptions" also do not work to fix this issue. does anyone have a work around for this?

Here is my actual code:

%Constant Values
A=1;                   %VOLTS
b0=1;                  %DIMENSIONLESS
r=0.75;                %DIMENSIONLESS
xn=ones(1,41);         %Input Sequence as a matrix equal to the Unit-Step Sequence in VOLTS (always 1) 
n=[0:1:40];            %Value of "n" ranges from 0 to 40 and are in 1 unit increments
%Impulse response of a 2nd-Order Infinite Impulse Response (IIR) Filter
hn=b0*(-r).^n.*(n+1);  %Creates a matrix of values from h[0], h[1], h[2],...,h[n-1],[n]
%Cumulatively sums the values of h[n] which yields the Output Sequence "y[n]"
yn=cumsum(hn);
N=n(:);               %Transforms matrix of values of "n" into a single column
XN=xn(:);             %Transforms matrix of values of "xn" into a single column
HN=hn(:);             %Transforms matrix of values of "h[n]" into a single column
YN=yn(:);             %Transforms matrix of values of "y[n]" into a single column
T = table(N, XN, HN, YN) %Outputs a table with the values of "n," the input sequence "x[n],"
                         %the 2nd-Order (IIR) filter "h[n]," and the output sequence "y[n]."
%T.Properties.VariableNames = {'n' 'x[n] (V)' 'h[n]' 'y[n] (V)'}
T.Properties.VariableNames{2} = 'x[n] (V)'

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the cyclist 2017-4-18

I've formatted your code for you. Next time, please use the "{}Code" button.

James Long 2017-4-18

the cyclist: Sorry about that. Brand new to MATLAB and these forums.

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Answer 1

Aniruddha Katre 2017-4-18

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You get this error message because 'x[n] (V)' is not a valid MATLAB variable name. The columns in a table are actually MATLAB variables, so the column header must be a valid variable name. There are 3 rules for a valid variable name that need to be followed:

Can only have letters, number and underscores in a variable name. Nothing else is allowed.
Variable names have to start with a letter.
Variable names can be up to 63 characters long.

'x[n] (V)' -- starts with a letter but has special characters such as brackets, specs and parenthesis in it which makes it an invalid variable name.

If you replace that with:

T.Properties.VariableNames{2} = 'x_n_V'

or something along those lines, that will work.

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James Long 2017-4-18

Aniruddha, thank you. I ended up exporting the data to an excel spreadsheet and there were no more issues. I appreciate the information on the constraints of Variable Names..will definitely assist in the future!

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