Add time column to matrix with measured values

I have text file with two columns - temperature and humidity. I have read the file into MatLab matrix. How can I add date/time column to this matrix? Logging started 1/1/2017 13:00:00 and it logged after every 0.5 sec.

Answer 1

[Andrei Bobrov]

T_out = timetable(datetime(2017,1,1,13,0,.5*(0:size(M,1)-1)'),M);

Answer 2

[KL]

m_time = datetime('1/1/2017 13:00:00'):seconds(0.5):datetime('1/2/2017 13:00:00');
T = table(m_time',temperature,humidity);

or

TT = timetable(temperature,humidity,'RowTimes',m_time');

[Fred]

Thank you! But unfortunately I am quit beginner, so how exactly do I add time column to matrix?

M = dlmread('temp_hum.txt');        % Load text file.
M = 

     1     2
     3     5
     7     2
     1     6
     5     9
     4     7
     1     9
.....
m_time = datetime('1/1/2017 13:00:00'):seconds(0.5):datetime('1/2/2017 13:00:00');
T = table(m_time,temperature,humidity);
dlmwrite('temp_hum_time.txt',M, ';')        % Save to text file.

[KL]

You've only mentioned your measurement frequency. How long do you have the measurement from "1/1/2017 13:00:00"?

m_time = datetime('1/1/2017 13:00:00'):seconds(0.5):datetime('YOUR END TIME HERE');

Then you should transpose this and create the table with your M matrix.

T = table(m_time',M);

Then you could use writetable function,

writetable(T,'temp_hum_time_v1.txt','Delimiter',' ');

[KL]

MOVED Fred's Answer to Comment:

Thanks a lot! I got it working. But one thing - if I don't know the end time of measurement, I only have text file with N-rows of measured data (sometimes 100 values, sometimes 128909 values and so on..). Is it somehow possible to calculate the ending time based on text file rows?

m_time = datetime('1/1/2017 13:00:00'):seconds(0.5):datetime('YOUR END TIME HERE');

[KL]

You should be able to calculate the end time anyway. What's the size of matrix M? Let's say your matrix M has 'n' rows, then you should create m_time such that it gets n rows as well.

n = size(M,1);
end_time = datetime('1/1/2017 13:00:00.00','Format','MM/dd/yy HH:mm:ss.SS') + seconds(0.5)*(n-1); %EDIT: added format to display millisecond
m_time = (datetime('1/1/2017 13:00:00.00','Format','MM/dd/yy HH:mm:ss.SS'):seconds(0.5):end_time)'; %EDIT: added format to display millisecond

Then create the as I explained before and use the writetable.

Goodluck!

Answer 3

[Fred]

Thanks a lot! I got it working. But one thing - if I don't know the end time of measurement, I only have text file with N-rows of measured data (sometimes 100 values, sometimes 128909 values and so on..). Is it somehow possible to calculate the ending time based on text file rows?

m_time = datetime('1/1/2017 13:00:00'):seconds(0.5):datetime('YOUR END TIME HERE');

Answer 4

[Fred]

Nice! Thank You!