MATLAB: How to read numerics as strings with readtable

Question

I have a table in spreadsheet (xlsx). One of the column is composed of either a numerical number, or several of them, like the below:

2
3 
5,7
9
7
4
2,8,9
5

When I use readtable:

T1 = readtable ('Observations.xlsx');

the results are like this:

2
3 
NaN
9
7
4
NaN
5

My question is how do I read the info as a string, so that the groups like '5,7', and '2,8,9' are all captured?

I tried:

T1 = readtable ('Observations.xlsx', 'Format','%s %s %s');

But got the below error:

Invalid value for "Format". Must be "auto" for spreadsheet files.

Answer 1

opts = detectImportOptions(yourfile);
opts = setvartype(opts, whichevervariable, 'string');  %or 'char' if you prefer
data = readtable(yourfile, opts)

Where whichevervariable is a char vector, cell array of char vector, string array containing the name(s) of the variable(s) that must be read as string/char or a numeric vector of variable indices.