Time vector

I have 1000 data points and know that they were opbtained with 1Hz sampling. I also have begining time: Begining time = 12:00:00

How would I make a time vector? such that I can plot the data vs time and able to pick out a datapoint and know it's coorespoinding time.

Thank you!

Answer 1

[Alex]

Do you want the answer in hh::mm::ss format?

sample_index = (selected sample index);
%elapsed time in seconds
elapsed_time = sample_index*(1/frequency);

%hoping you have start time in seconds and not in a string
time_at_sample = elapsed_time + start_time;

tot_seconds = time_at_sample
%convert to str
hour = fix(tot_seconds / sec_in_hour);
tot_seconds = mod(tot_seconds, sec_in_hour);
min = fix(tot_seconds / sec_in_min);
sec = mod(tot_seconds, sec_in_min);

time_str = sprintf('%i%i%i', hour, min, sec);

Answer 2

[the cyclist]

Here's one way:

basetime = [2011 01 01 12 0 0]; % Arbitrary date, starting at noon
basetimeVec = repmat(basetime,[1000 1]);

basetimeVec(:,6) = (0:999)'; % Add one second at a time (because 1 Hz rate)

timevec = datenum(basetimeVec); % MATLAB datenum format
datestr(timevec); % String with the time

Answer 3

[Fangjun Jiang]

StartTime=datenum(2011,10,31,12,00,00);
OneSecond=1/3600/24;
TimeVector=StartTime+OneSecond*(0:1000);
datestr(TimeVector)