How to change the date format of ,txt file?

Hi, I am having a hard time on this. I need to read a sequence of .txt files (wind speed and direction forecasts).

I am storing the files names in an array called modfile:

t1 = datetime(2019,7,2);
a=dir(('C:\Users\jmarc\PGE\Dados\Previstos\*.txt'));
numfiles=size(a,1);
mydata = cell(1, numfiles);
for k = 1:numfiles
  dia=sprintf( '%02d', day(t1));
  mes=sprintf( '%02d', month(t1));
  ano=sprintf( '%04d', year(t1));
  amd=[ano,'-',mes,'-',dia];
  myfiletxt=['C:\Users\jmarc\PGE\Dados\Previstos\','Previsao_Total_',amd,'.txt'];
  modfile(k)=string(myfiletxt);
  t1=t1+1;
end
for i=1:length(modfile)
    modi = readtable(modfile(i));
...

The timestamp of the first column of each file is like this:

2019-07-02 0:30:00

It turns out when matlab reads the timestamp (modi file), day and month are reversed.

Instead of 02-Jul-2019, it gives 07-Feb-2019.

I tried many different formats when reading modfile(i), but I was not successful.

Does anyone can help me?

[Ilian]

Have you tried to use the textscan function to read the file? There you can specify the date format. See here for an example:

https://www.mathworks.com/help/matlab/ref/textscan.html

[JOAO LIMA]

Thanks, Ilian! I will try it.

[dpb]

Use the detectImportOptions function to create a DelimitedTextImportOptions object for the file. In it you can set the 'DateFormat' for the date/time variable(s) with the setvaropts function.

Then pass the object when call readtable.

Same effect as w/ textscan but get the table directly as well as avoid fopen-fclose hassle and the need to then convert the raw data to the table.

[JOAO LIMA]

Thanks for your support! Actually I realize that problem starts when I write the txt files from a excel files.

I am using xlsread to load the excel files, extracting sheet #4, and write it in txt format.

I am working on it, but not yet fixed.

[dpb]

xlsread has been deprecated--use one of the suggested alternatives at doc xlsread depending on the format of the data in the sheet..

[JOAO LIMA]

dpb, I got it, following your first answer. See below.

Answer 1

[Jeremy Hughes]

https://www.mathworks.com/matlabcentral/answers/516121-how-do-i-specify-a-datetime-format-when-reading-a-csv-excel-file

[JOAO LIMA]

Thank you!! I really worked! Just one thing: for me worked 'DatetimeFormat' instead of 'DateTimeFormat'

opts = detectImportOptions(modfile(i));

opts = opts.setvaropts('data11','InputFormat','dd/MM/yyyy HH:mm:ss','DatetimeFormat','dd-MMM-yyyy HH:ss');

modi = readtable(modfile(i),opts);

[Jeremy Hughes]

BTW, if the format of the files are all the same, you can re-use the opts

opts = detectImportOptions(modfile(1));
opts = opts.setvaropts('data11','InputFormat','dd/MM/yyyy HH:mm:ss','DatetimeFormat','dd-MMM-yyyy HH:ss');
for i = 1:numel(modfile)
    modi = readtable(modfile(i),opts);
end