MATLAB: How to control the xticks if x is a long imported excel column (Time Format: HH:MM:SS)

excelimporting excel datatimetime series

How can I show out of the 1700 values of a time column (in HH:MM:SS format), only a couple of them in the x axis? Do I have to change the time format into a double value to define how it should be in the x axis?

Best Answer

Try this out: Since I didn't have your variable class, I had to assume you're dealing with time-stamps here. This works for those:
    t1 = datetime(2020,8,12,13,11,24); %start time
    t2 = datetime(2020,8,12,13,18,36); %end time
    time5 = t1:seconds:t2; %create a vector of time points from the start time to the end time
    v5 = randn(size(time5)); %create random y-axis data
    plot(time5,v5) %plot data
    hold on; %hold the current figure so the first plot doesn't erase when you do the 2nd plot
    avg5 = mean(v5); %the average value of v5
    x2= [time5(1) time5(end)]; %x-values for the average line
    plot(x2,[avg5 avg5], 'y-', 'LineWidth',2); %plot the avg line
    title('value 5 by time plot') %title the plot
    legend('Raw data','Average line') %add a legend to differentiate the two data sources
    ax = gca; %get current axis
    x_step_size=100; %step size between labels in seconds
    ax.XAxis.TickValues = t1:seconds(x_step_size):t2; %adjust the tick values to the correct spacing
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