How to set datetick at 10 minute intervals when data starts at random times

I have several data sets that start at random times (e.g., 10:04:23, 08:27:59, etc). The time is in the serial date format which I use datetick to change to the mm/dd/yy HH:MM format . I am plotting experimental data versus time via a function. I want to plot the data every 10 minutes but I want the intervals to be multiples of 10. For example, if my data starts on Aug 1, 2013 10:04:23 I want my first tick mark to read 8/01/13 10:00 and show every 10 minutes until the end of the data. Because each data set starts at a different time I cannot just write a simple time subtraction function that would apply to all.

I am wondering if there is a way to get the time axis to plot every 10 minutes on a multiple of 10 minute using a loop or if/else statement. I do not want to have to go in and manually change the start tick each time.

Within my function I have the following where tenmin is 10 minutes as a serial date, start is the first time of the data and last is the end time of the data:

tenmin = 0.006944444496185;
set(gca,'XTick',[start:tenmin:last])

Thank you for any insight and help. -P. Wallace

Answer 1

[Walter Roberson]

tickstart = floor(start * 24 * 60 / 10) / (24 * 60 / 10);

now you can use tickstart:tenmin:last

[Pw]

Thank you! Clean & simple.

Answer 2

[Kelly Kearney]

I wrote this a little function ( datelist.m ) for exactly this purpose (although in my case, I usually want to label all months, where datetick tends to opt for annoying quarterly ticks by default). Works for any time interval...

start = datenum('01-Aug-2013 10:04:23');
last = datenum('01-Aug-2013 12:00:00');
t = linspace(start,last,100);
y = rand(size(t));
plot(t,y)
tk = datelist(start, last, 1:12, 1:31,1:24,0:10:60);
set(gca, 'xlim', [start last], 'xtick', tk)
datetick('keepticks', 'keeplimits')

[Pw]

This works great, exactly what I needed. Thank you!

[Trung Hieu Le]

Hi Sirs,

Do you keep the file (datelist.m) which I expect to follow for my case? Because I cannot get some points in your help. Thanks

[Walter Roberson]

Kelly moved the repository; you can find it at https://github.com/kakearney/datelist-pkg