Error using readtable, Input must be a row vector of characters or string scalar: WHERE IS YOUR PROBLEM??

Hi guys.

My problem is rather common but I cannot solve it. I have several .csv files that I want to combine into one (same sheet). I am trying

vars={'Temperature'; 'Relative humidity'};
path = append(output_path,'\',stations{i},'\');
files = append(path, 'Stats ', months ,' ', stations{i} ,' ',vars{1},' .csv'); 
result = table();         
for fidx = 1:numel(files)
   filecontent = readtable(files); 
   [~, filenumber] = fileparts(files(fidx).name);
   filecontent.file_label = repmat(str2double(filenumber), height(filecontent), 1);
   result = [result; filecontent];
end

Just to help you understand, stations{i} come from the attached .xlsx and the attached .csv is one of the many files I want to combine. When I run these lines I get the message "Error using readtable, Input must be a row vector of characters or string scalar". I tried files = char(files) but it didn't work.

Any ideas please???

PS. I am on 2019a.

Answer 1

[Fangjun Jiang]

readtable() can read one file at a time. Your "files" variable seems to contain multiple files. So you can't use readtable(files). Most likely, you need to use readtable(files{fidx})

Whenever there is an error, try to debug it yourself. Put a break point in the code, run the code line by line, check out the value of each variable, and look at the error message.

[Daphne PARLIARI]

Great, I tried what you suggested and it worked. Of course I tried to debug myself but obviously I missed it. Thank you for your help!

Nevertheless, now it stops in the next line with the error "Dot indexing is not supported for variables of this type."

Any ideas?

[Walter Roberson]

Your files variable is not the output of a dir() call. It appears to be a cell array of character vectors.

[Daphne PARLIARI]

Exactly Walter. I used append in the 3rd line instead of dir because the filenames I want to "extract" are dynamic, AKA months ,stations{i} and vars change.

What can I do to overcome this?

[Fangjun Jiang]

which line causes the new error message? Your code requires output_path,stations{i}, etc. which are not provided.

[Daphne PARLIARI]

This line causes the problem: [~, filenumber] = fileparts(files(fidx).name);

stations{i} come from the attached .xlsx and based on the weather station names I created respective folders.

output_path is the path where all .csv are saved in my computer.

I am also attaching 2 .csv to help you understand.

[Fangjun Jiang]

so pause your running program at this line, check the value of "fidx", "files" and run "files(fidx)", "files(fidx).name" in Command Window. You will see the exact same error message. You have to ask youself what do you mean and why do you run "files(fidx).name"?

[Daphne PARLIARI]

You were right. I fixed my code as follows, in case someone has the same problem with me:

path = append(output_path,'\',stations{i},'\');
files = append(path, 'Stats ', months ,' ', stations{i} ,' ',vars{1},' .csv'); 
result = table();         
for fidx = 1:numel(files)
   filecontent = readtable(files{fidx}); 
   [~, filenumber] = fileparts(files{fidx});               
   filecontent.file_label = repmat(str2double(filenumber), height(filecontent), 1);
   result = [result; filecontent];
end
outfile = [output_path,'\',stations{i},'\','Monthly T stats ',stations{i},' 2015.xlsx'];
writetable(result,outfile);

Thanks everyone for your contribution!