Plotting x-axis time in dd hh mm ss format

Question

Calum 2023-4-4

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编辑： Bora Eryilmaz 2023-4-11

Hi folks, hope you are well.

I am just wondering if anyone has any experience with gps-type time scales for plotting. I am plotting a series of interactive plots and already have my x parameter (time in seconds) and my y parameters to match. However, I also have a matching time dataset which is in dd hh mm ss format, for day, hour, minute, second - where day started on the 1st january this year (locally).

I would really like to explore the possibility of having my x-axis time scale in the form dd hh mm ss as is given in the data, whilst STILL having the iteractivity component of these plots. i.e. being able to zoom and scale with the time snapping to ajust.

I have looked through plenty answers but can't find much help with what exactly i'm trying to do - hope someone can help!

Many thanks,

C.

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Answer 1

Bora Eryilmaz 2023-4-4

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编辑：Bora Eryilmaz 2023-4-11

在 MATLAB Online 中打开

You can use the datetime data type for the x-axis values and adjust the date/time format as you like:

now = datetime;

x = now + seconds(0:10)/7;

y = rand(1,11);

plot(x,y)

ax = gca;

ax.XAxis.TickLabelFormat = 'HH:mm:ss.SSS';

ax.XTickLabelRotation = 45;

t = 4.3860e+04 + (0:100)/pi; % An array of seconds starting at 4.3860e+04 seconds.

ts = seconds(t); % Convert it to duration in seconds.

ts.Format = 'hh:mm:ss.SSS';

y = rand(size(t));

plot(ts,y)

ax = gca;

ax.XTickLabelRotation = 45;

All the zoom, pan, etc, behaviour would continue to be functional.

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Bora Eryilmaz 2023-4-5

See updated code.

Calum 2023-4-11

Thank you! This now seems to be working! The only problem is that I can't seem to get milliseconds as this format 'SSS' doesnt seem to be recognised on the 2020b version I am using, but the hh:mm:ss form is good enough - thanks!

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Answer 2

Steven Lord 2023-4-5

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https://ww2.mathworks.cn/matlabcentral/answers/1941039-plotting-x-axis-time-in-dd-hh-mm-ss-format#answer_1209779

在 MATLAB Online 中打开

Based on the clarifications you posted on the answer by @Bora Eryilmaz I think you want to plot a duration array rather than a datetime array. As an example let's take 10 values randomly generated as a number of seconds between 0 and 3 hours.

s = sort(randi([0 seconds(hours(3))], 1, 10))
s = 1×10
         321         715        1846        3672        4857        5154        7973        8208       10024       10397

Create a duration array from s by calling seconds on it. seconds, minutes, hours, etc. can accept either a duration or a number and converts to the other type. I used it in both senses above; hours(3) to convert a number to a duration and seconds on the duration to returns the number of seconds in 3 hours.

t = seconds(s)
t = 1×10 duration array
     321 sec     715 sec    1846 sec    3672 sec    4857 sec    5154 sec    7973 sec    8208 sec   10024 sec   10397 sec

Let's change its Format. This doesn't change the data, just how it's displayed to the user.

t.Format = 'hh:mm:ss'
t = 1×10 duration array
   00:05:21   00:11:55   00:30:46   01:01:12   01:20:57   01:25:54   02:12:53   02:16:48   02:47:04   02:53:17

and now we can plot.

plot(t, 1:10, 'o-')

You can't zoom on the picture here on MATLAB Answers, but if you were to run this code in an interactive MATLAB session you could and you'd see the X axis update.