MATLAB: How to set dates for x-axis

axisdateformatplottick

Hey everyone,

I know this has been discussed on the internet numerously, but I still cannot find a solution to my problem:

I am using a date vector that contains dates and times from

 start=datenum(2010,05,15,0,0,0);

 fin=datenum(2010,05,30,23,0,0);

So each day contains 24 values (for the 24 hours of the day).

Now I want to plot some data for these dates and I want a tick for each day on my x-axis and a label for each tick like this: May 15, May 16, May 17 …. May 30. The tick should be in the middle of each day, so every day at 12 o'clock would be great. How can I do that?

Thanks a lot!!

Best Answer

This works:

start = datenum(2010,05,15,0,0,0);
fin=datenum(2010,05,30,23,0,0);
hrvct = start:(1/24):fin;                           % Create Hourly Dates
dtks = start+0.5:fin;                               % Ticks At Noon
dhv = datevec(dtks);
y = (0:length(hrvct)-1)*0.005-sin((0:length(hrvct)-1)/24*2*pi+0.25)*5+randn(size(hrvct))*0.05+20; % Create Y-Data
figure(1)
plot(hrvct, y)
grid
set(gca, 'XTick', dtks, 'XTickLabelRotation',30)    % Label Rotation (R2014b)
datetick('x', 'mmm dd', 'keepticks')
xlabel('Time')
ylabel('Temperature (\circC)')

You have to have R2014b to use the 'XTickLabelRotation' property. Otherwise, either reduce your x-axis font size or use the text function to create a vector of rotated dates.

Example plot:

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I didn’t use a datetime array here and used the older date formats instead. This does what you want for the sample data I plotted.

The Code —

dnv = datenum([2016 10 31]):datenum([2017 04 30]);              % Date Number Vector
dvm = datevec(dnv);                                             % Date Vectors (For End-Of-Month Calculation)
dmm = unique(dvm(:,1:2), 'rows');                               % Unique Years & Months
eoms = eomday(dmm(:,1),dmm(:,2));                               % Find End-Of-Month Days
xtix = datenum([dmm eoms]);                                     % Date Numbers For End-Of-Month Days
xtix(1:end-1) = xtix(1:end-1)+1;                                % Add ‘1’ To All But Last
xdata = dnv(2:end);                                             % Create Data
ydata = rand(1, length(xdata))*10 - sin((0:length(xdata)-1)*pi/length(xdata))*25 + 10;
figure(1)
plot(xdata, ydata)
grid
set(gca,'YLim',[-30 30])
set(gca, 'XTick',xtix)
datetick('x', 'mmm dd', 'keepticks')

Your files contain only the dependent variable, so it will probably be relatively straightforward for you to adapt my code here to your data by substituting it for ‘ydata’.

The Plot —

MATLAB: How to format the axis of the plot

%OPTION 1: Overwrite the XTickLabel property of the axes. (Simpler code but messy plot)
plot([1:10]*10^6, 1:10)
XTick = num2cell(get(gca, 'XTick'));
XTickLabel = cellfun(@(x) sprintf('%0.0f', x), XTick, 'unif', false);
set(gca, 'XTickLabel', XTickLabel, 'XTickLabelRotation', 90)
%OPTION 2: Determine what power was used, then adjust the x-axis name and XTickLabel. (Cleaner plot)
plot([1:10]*10^6, 1:10)
XTick = get(gca, 'XTick');
XTickLabel = get(gca, 'XTickLabel');
XTickLabelNum = str2double(XTickLabel{end});
Power = log10(XTick(end)/XTickLabelNum);
if Power ~= 0
  xlabel(sprintf('X TEXT (x 10^{%d})', Power))
else
  xlabel('X TEXT')
end
set(gca, 'XTickLabel', XTickLabel)

Best Answer

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