How to plot time data at different intervals?

Hi all

I have data as follows:

Date: (Column 1)

08:06:2012

08:06:2012

09:06:2012

10:06:2012

13:06:2012

Time:(Column 2)

13:56:52

13:59:32

14:08:27

03:05:48

03:11:34

var_1:(Column 3)

0.448584

0.445232

0.414100

0.236846

0.239984

I want to plot var_1 but as you can see, the date and time are not given at same intervals. If I create an array with all seconds for all days (so that they are equally spaced), then it would take a lot of space since I have 3 years of data.

Any suggestions on how to plot this without creating an equally spaced time intervals with blank values for missing data of var_1 in the data file? I still need to have the gaps of missing date/time data on my plots though. I tried using the timeseries code as below, but it doesn't work because it still requires my data to be equally spaced...

x = var_1;
ts1 = timeseries(x,1:6);
ts1.Name = 'Secondsly Count';
ts1.TimeInfo.Units = 'seconds';
ts1.TimeInfo.StartDate=Date(1,1);
ts1.TimeInfo.Format = 'mmm dd, yyyy HH:MM:SS';   
ts1.Time=ts1.Time-ts1.Time(1);        
plot(ts1)

Thank you.

[Stephen23]

Most plot commands in MATLAB don't need evenly spaced data... try it, and see what happens!

Answer 1

[Star Strider]

If you want to plot them, the interval between the measurements should not be a problem. They don’t have to be equally-spaced. Combine the date and time, create date numbers from them with datenum, and plot. Use datetick to help with your x-axis tick labels.

[B.kun]

Thank you for the suggestion! This is what I tried and it worked: I combined the date and time into one column and plotted using the datetick.

DateTime = datenum(Date) + datenum(Time) - datenum('00:00','HH:MM');
%newdatecolumn = datestr(DateTime);
figure
plot(DateTime,var_1,'o')  
dateFormat = 'dd-mm-yy';
datetick('x',dateFormat)

I hope this works with my original huge dataset too.. ^^"

[Star Strider]

My pleasure!