matlab - Plotting with respect to minutes as formatted time (min.sec)

Question

I'm trying to plot some data with respect to minutes instead of seconds in Matlab as formatted time, i.e. min.sec.

I have real time data streaming in where with every sample received, its time in seconds is also sent. I then plot them with respect to time. Now, since my session is around 15 minutes long, I can't be plotting with respect to time. Therefore I wanted to plot it with respect to time (min.sec). I tried dividing the received time by 60 but this gives me minutes with 100 subdivisions instead of 60 (the minutes increment after 0.9999 instead of 0.59). How do I convert it so that I'm able to plot with respect to time in minutes?

Here is what I mean by 0.99 fractions of a minute instead of 0.59. A normal minute has 60 divisions not 100.

EDIT: I tried m7913d's suggestions and here is what I got.

1. first I plot the signal with respect to time in seconds without changing the ticks ( A normal plot(t,v))

2. The I added datetick('x', 'mm:ss'); to the plot (Xtick format is not supported in Matlab 2015b)

Here is a screenshot of the results

The time in seconds was up to 80 seconds, when translated into minutes, it should give me 1 minutes and 20 seconds as the maximum x axis limit. But this is not the case. I tried to construct a t vector (i.e like t=0:seconds(3):minutes(3)) but I couldn't link it to my seconds vector which will be constantly updating as new samples are received from the serial port. Thanks

Answer 1

You can use xtickformat to specify the desired format of your x labels as follows:

% generate a random signal (in seconds)
t = 0:5:15*60;
y = rand(size(t));

plot(seconds(t),y) % plot your signal, making it explicit that the t is expressed in seconds
xtickformat('mm:ss') % specify the desired format of the x labels

Note that I used the seconds methods, which returns a duration object, to indicate to Matlab that t is expressed in seconds.

The output of the above script is (the right image is a zoomed version of the left image):

Pre R2016b

One can use datetime instead of xtickformat as follows:

datetimes = datetime(0,0,0,0,0,t); % convert seconds to datetime
plot(datetimes,y)
datetick('x', 'MM:SS'); % set the x tick format (Note that you should now use capital M and S in the format string
xlim([min(datetimes) max(datetimes)])