array2table won't accept variable name input

I am attempting to turn an array into a table before I output it into a file, and I am running into an error when I attempt to try and put variable names into my table.

data = randi(100,10,5);
headers = {'T','1','2','3','4'};
tabl = array2table(data,'VariableNames',headers);

Error using array2table (line 62)

'1' is not a valid variable name.

Error in TestCode (line 3)

tabl = array2table(data,'VariableNames',headers);

I don't understand why '1' is not a valid variable name. Can I not use numbers, even when they're a string? I have confirmed the class is 'char' for the actual contents of the headers cell, but it still doesn't seem to like it.

Answer 1

[Jan]

Which Matlab version are you using? In the current version 2021a I find:

doc table
% Variable names can have any Unicode® characters,
% including spaces and non-ASCII characters.

Your code run without problems.

In former Matlab versions the variables of tables needed to be valid Matlab symbols: < 64 characters, ASCII, no spaces, initial character cannot be an underscore or digit.

[Bob Thompson]

I'm using 2016b, so it has to start with a letter, and can't contain spaces.

Answer 2

[Sean de Wolski]

Support for invalid variable names was added recently so you're probably on an older release that required >>isvarname(varname) to be true.

You can

1. upgrade
2. call: matlab.lang.makeValidName to turn your names valie
3. Change the names to valid yourself "One", "Two" would be valid...

[Bob Thompson]

Unfortunately, I'm not capable of upgrading.

I'm also not sure if I am capable of modifying the validity of names, and would prefer to avoid that option.

So, in the end I did end up changing the names by adding an alphabetical character at the beginning of each number.