How to convert date by changine date format from text file?

I'd like to convert date according to first three column as day-month-year hour:minute:second.

• A column: Year
• B column: Day of the year
• C column: Hour

I tried to do it, not achieving.

Answer 1

[Kojiro Saito]

Simply, you can utilize table's functioinalities.

t = readtable('test5.txt');

% Create datetime and display as "day-month-year hour:minute:second" format
dt = datetime([t.Var1 ones(height(t), 1) t.Var2 t.Var3 zeros(height(t), 1) zeros(height(t), 1)], 'Format', 'dd-MM-yyyy HH:mm:ss');

% Insert datetime variable to the table as "datestr" column
t.datestr = dt;

% Write a table as a file
writetable(t, 'output.txt')

UPDATED

Based on your comment, the following is what you want. removevars and movevars were introduced in R2018a.

t = readtable('test5.txt');

% Convert to datetime
dt = datetime([t.Var1 ones(height(t), 1) t.Var2 t.Var3 zeros(height(t), 1) zeros(height(t), 1)]);

% Insert datetime variables to original table
t.datestr = datetime(dt, 'Format', 'dd-MM-yyyy');
t.timestr = datetime(dt, 'Format', 'HH:mm:ss');

% Delete column 1 to 3
T2 = removevars(t, 1:3);
% Move datestr and timestr to the first and second columns 
T2 = movevars(T2, {'datestr', 'timestr'}, 'Before',1);

% Write table as a tab separated file without headers
writetable(T2, 'output.txt', 'WriteVariableNames', false, 'Delimiter', 'tab')

[Dogan Deniz Karadeniz]

I think I didn't explain myself clearly.

Output should be as follow

29-06-2012 00:00:00    30    25    21.2

[Kojiro Saito]

I've updated the answer.

Answer 2

[Himanshu Rai]

Try this function, it accepts three vectors corresponding to year, day and hour

function Dt = conv(Year, Day, Hour)
    Dt = datetime(Year, 1, 1) + Day - 1 + hours(Hour);
end    

[Dogan Deniz Karadeniz]

How to input data and write it to text file again?

>> conv
Not enough input arguments.

Error in conv (line 2)
    Dt = datetime(Year, 1, 1) + Day - 1 + hours(Hour);

[Himanshu Rai]

You don't have to call this like - conv.

Suppose your data are stored in Year, Day and Hour column vectors, then use the following statement

conv(Year, Day, Hour)

[Dogan Deniz Karadeniz]

Sorry, I don't understand.

[Himanshu Rai]

I will give an example

Year = 2000:2020; % your year vector
Day = 20:40       % your day vector
Hour = 0:20       % your hour vector
conv(Year, Day, Hour)    % calling the function with the arguments

[Himanshu Rai]

If you want to read data from the file, use this link - textscan. However note that this was not what was specified in your question. If you want something else please specify it clearly in your question.

[Dogan Deniz Karadeniz]

Sorry about that. Indeed, I need to write output other columns together in the text file.