How to plot Date time series in MATLAB?

I am facing difficulties in plotting my time series data.The data file is also attached.I write code like this but doesnt work.

data3=readtable ('PRICE_AND_DEMAND_Jan.csv')

Date_Time = data3(:,2);
datecell=table2cell(Date_Time);
load = data3(:,3);
A = table2array(load)
p=datenum(datecell);
plot(datenum(datecell), A)
datetick('x', 'dd-mmm-yyyy HH:MM:SS')
% datetick('x', 'dd-mmm-yyyy HH:MM:SS')

[madhan ravi]

Which version of matlab are you using?

[Ali]

Matlab 2018b.

I think MATLAB in my computer has changed the default settings of date reading.It by deafault reads dates in YYYY-MM-DD format.

Seriously,this plotting problem is irritating now.

[Peter Perkins]

You have dates like xx-yy-zz. That's kind of ambiguous. You'll want to provide a format.

Answer 1

[Ricardo MF]

Try it:

data3=readtable ('PRICE_AND_DEMAND_Jan.csv')
Date_Time = data3(:,2);
datecell=table2cell(Date_Time);
load = data3(:,3);
A = table2array(load)
formatIn='dd-mm-yy HH:MM'
p=datenum(datecell,formatIn);
plot(p, A)
datetick('x', 'dd-mmm-yyyy HH:MM')
set(gca,'XTickLabel',datestr(p),'XMinorGrid','on')
grid

[Ali]

Thank you Ricardo but i am getting this error .Have you checked the attached data file (.csv) in previous file?

[Ricardo MF]

I do not get this error. Let me check.

[Ali]

Thank you for your time.

[Ricardo MF]

Still with a problem to 'calibrate' the x axes but the code 'works'.

clear all
close all
data3=readtable ('PRICE_AND_DEMAND_Jan.csv')
Date_Time = data3(:,2);
datecell=table2cell(Date_Time);
load = data3(:,3);
A = table2array(load)
formatIn='dd-mm-yy HH:MM'
p=datenum(datevec(datecell,formatIn));
plot(p,A)
datetick('x', 'dd-mmm-yyyy HH:MM')
set(gca,'XTick',p([1 size(p,1)/4 size(p,1)/2 (size(p,1)/4)*3 end]),'XTickLabel',datestr(p),'XMinorGrid','on','FontSize',7)
grid

[Ali]

Still i am getting error due to formatting in Date and time as shown in attached image.Can you pls check the formatting of date and time.There is something wrong there.

Answer 2

[Ricardo MF]

Are you running the entire code or assuming you already 'uploaded' the variables? The problem is with the format of your variable Date_Time that for some reason converted to a 'char' vector. Instead mine's not. When I convert to datecell, I do not have problems with datenum or datevec. Maybe this problem is related to the version of matlab as questioned by madhan ravi.

[Ali]

I am running the entire code you posted above.I think my PC Matlab is reading the dates incorrectly.Is there any command to reset the date preferences in MATLAB?

Answer 3

[Peter Perkins]

In something as recent as R2018b, stay away from datenum and datetick if possible. (Also, hardly ever does one need table2cell, brace subscripting would have done the same thing, but you don't want to do that thing anyway.)

Try this:

>> t = readtable('PRICE_AND_DEMAND_Jan.csv','Format','%s%{dd-MM-yy HH:mm}D%f%f%s');
>> t.REGION = categorical(t.REGION);
>> t.PERIODTYPE = categorical(t.PERIODTYPE);
>> head(t)
ans =
  8×5 table
    REGION    SETTLEMENTDATE    TOTALDEMAND     RRP     PERIODTYPE
    ______    ______________    ___________    _____    __________
     NSW1     01-01-19 00:30      7457.6       66.95      TRADE   
     NSW1     01-01-19 01:00      7243.2       69.33      TRADE   
     NSW1     01-01-19 01:30      6918.6        72.8      TRADE   
     NSW1     01-01-19 02:00      6676.6       70.31      TRADE   
     NSW1     01-01-19 02:30      6513.2       66.98      TRADE   
     NSW1     01-01-19 03:00        6400       63.87      TRADE   
     NSW1     01-01-19 03:30      6317.4        62.2      TRADE   
     NSW1     01-01-19 04:00      6242.1       50.22      TRADE   
>> plot(t.SETTLEMENTDATE,t.TOTALDEMAND);

[Ali]

I tried the above code but it only displays date on x-axis.I need to display time as well as it is important for my results.Many thanks.Secondly,can you pls tell me few lines on this command

D%f%f%s'

[Peter Perkins]

I doubt that you want the time on a plot that covers an entire month. But zoom in, and the times will appear when you get close enough. In any case, you can set the properties of the x axis to get exactly the date/time format that you want. get gca, and dig in to its properties.

%s%{dd-MM-yy HH:mm}D%f%f%s is a quick way to read the file and provide a format for the timestamps. More control is available using detectimportoptions.

[Ali]

Thank you peter for your useful reply.How to set time and date limits on x-axis? i tried to use "xlim" but it give me errors.for instance:

start time  =01-jan-2016 00:00
end date    =01-jan-2016 23:30

[Peter Perkins]

You are going to need to post something more than that. That is not MATLAB code. In recent versions of MATLAB, all you need to do it set xlim with datetimes.