datetime adjustment in x-axis plot

Hello everyone,

I want to adjust my datetime x-axis in pcolor plot in matlab but I tried but it isn't working. I give my data here and code below:

x  = [01-01-2021 00:00  01-01-2021 00:14  01-01-2021 00:28  01-02-2021 00:42] %like this one year data for 14 min intervel
y = [10.23  11.16  12.19  13.31  14.54  15.88  17.35  18.96  20.72  22.66  24.77  27.1  29.65  32.45  35.53  38.92  42.65  46.77  51.32]
z = [2.27E+03  3.94E+03  4.48E+03  6.26E+03  3.18E+03  3.78E+03  5.37E+03  5.60E+03  6.35E+03  8.47E+03  1.05E+04  1.05E+04 
    1.36E+04  1.12E+04  8.48E+03  3.96E+03  5.84E+03  4.55E+03  3.65E+03  6.17E+03  7.48E+03  6.98E+03  9.84E+03  1.11E+04  
    5.72E+04  6.90E+04  5.64E+04  4.71E+04  1.94E+04  6.37E+03  6.59E+03  6.89E+03  8.81E+03  9.70E+03  8.11E+03  9.59E+03  
    1.26E+04  1.34E+04  1.69E+04  1.99E+04  2.18E+04  2.62E+04  2.98E+04  9.09E+03  5.16E+03  8.73E+03  3.96E+03  4.95E+03 
    5.16E+03  4.06E+03  4.24E+03  6.17E+03  7.99E+03  8.20E+03  6.68E+03  1.07E+04  1.24E+04  1.36E+04  1.78E+04  1.89E+04]

Code:1

pcolor(datenum(x),y,z)
shading interp
a = gca;
set(a,'XTick');
datetick('x','dd-mmm HH:MM','keepticks','keeplimits'); # tried this it is showing only few date  points
%(or)
datetick('x','dd-mmm HH:MM','keepticks'); # tried this it is also showing only few date points

Code:2

pcolor(datenum(date1),y,z)
a = gca;
a.XTick = datenum(x);
a.XTickLabel = datestr(datenum(x)); # in this code it is taking as a text and displaying all the points

I just want to show in my x-axis like Jan, Feb, Mar, till Dec or daily one point or 10 days once one point like Jan 10 Jan 20 Jan 30 Feb 10 etc.

I tried a lot of things, but I wasn't able to make this. I am waiting for the help from the experts.

Thank you in advance.

[Dyuman Joshi]

What is this line supposed to do?

x  = [01-01-2021 00:00  01-01-2021 00:14  01-01-2021 00:28  01-02-2021 00:42] %like this one year data for 14 min intervel

Also, the dimensions of x (idk what the dimensions are), y (1x19) and z (1x36) do not match for making a pcolor plot.

What is the objective here? What are you trying to do?

Answer 1

[Steven Lord]

Stop using datenum. If you have the text form of a date and time, use datetime instead of creating a serial date number array. You can plot or pcolor using datetime data as the coordinates directly.

x = 0:10;
dt = datetime('today') + days(x);
plot(dt, x.^2, 'o-')

[vignesh mohan]

Thank you for your reply

It is not showing properly @Steven Lord

Answer 2

[Manikanta Aditya]

Hi @vignesh mohan

You can adjust the x-axis of your plot by setting the XTick and XTickLabel properties of the axes. Here’s how you can do it:

pcolor(datenum(x),y,z)
shading interp
a = gca;

% Set the XTick to be every 10 days
a.XTick = datenum('01-01-2021 00:00'):10:datenum('01-02-2021 00:42');

% Format the XTickLabel to display the date
a.XTickLabel = datestr(a.XTick, 'dd-mmm');

% Ensure the limits of the x-axis remain the same
xlim([datenum('01-01-2021 00:00') datenum('01-02-2021 00:42')]);

This code will set the x-axis ticks to be every 10 days, and the labels will be formatted to display the date in ‘dd-mmm’ format. The xlim function is used to ensure that the limits of the x-axis remain the same.

Hope this helps.

[vignesh mohan]

Hello Manikanta Aditya

Thank you for your reply

I tired your code but whenever i run your "a.XTick = datenum('01-01-2021 00:00'):10:datenum('01-02-2021 00:42');" my all the x-axis are not showing in the graphs

i change your code according to my timing

a.XTick = datenum('01-01-2021 00:00:00'):10:datenum('31-12-2021 23:48:00');

[Manikanta Aditya]

pcolor(datenum(x),y,z)
shading interp
a = gca;

% Set the start and end dates based on your data
start_date = datenum('01-01-2021 00:00');
end_date = datenum('31-12-2021 23:48');

% Set the XTick to be every 10 days within the data range
a.XTick = start_date:10:end_date;

% Format the XTickLabel to display the date
a.XTickLabel = datestr(a.XTick, 'dd-mmm');

% Ensure the limits of the x-axis remain the same
xlim([start_date end_date]);

Once, check with this.

[Aquatris]

So your x axis actually has 1 single element? I think you are not constructing your xlabel vector properly.

xVec = datenum('01-01-2021 00:00'):10:datenum('01-02-2021 00:42')

xVec = 738157

[vignesh mohan]

same like my all the x-axis are not showing in the graphs

I had attached my sample data set. kinldy check my file @Aquatris,@Dyuman Joshi,@Manikanta Aditya

code

x = [sample{2:end,1}];

y = table2array(sample(1,2:end));

z = table2array(sample(2:end,2:end));

pcolor(datenum(x),y,z)

shading interp

a = gca;