Change the format of an output figure of 'findchangepts'-function into datetime format.

Hi!

When I use a function such as

findchangepts(data.val)

it automatically produces a figure. Unfortunately, the x-axis just shows sample numbers as it is not possible to, for example, use a timetable as input...

But I want the figure in datetime format. Right now, it is very inconvenient to change the figure into a dateformat:

    [BPTipt, BPTresidual] = findchangepts(data.val) % my data gives me 2 change points
    findchangepts(data.val) 
    h = get(gca, 'Children');
%% define datenums for Children's xdata:
    t = datenum(data.Time(BPTipt));
    t1 = [t(1) t(1) NaN t(2) t(2) NaN]; % get the format to set children xData
    t2 = [datenum(data.Time(1)) t(1) NaN t(1) t(2) NaN t(2)  datenum(data.Time(end)) NaN]; % get the format to set children xData
%% set new datenums as xdata for Children:
    set(h(3,1),'xdata',datenum(data.Time));
    set(h(2,1),'xdata',t2);
    set(h(1,1),'xdata',t1);

    datetick('x','mmm yy','keeplimits','keepticks');

and that way I still don't have datetime format...

My questions:

• Is there an shorter easier way to get the output figure in a datetime format?
• If not, how can i change a figure with datenums as x-data to a datetime format?

Thanks!

Answer 1

[Seth Furman]

This same figure can be created with the relevant x data by using the plot, title, and xline commands.

https://www.mathworks.com/help/matlab/ref/plot.html

https://www.mathworks.com/help/matlab/ref/title.html

https://www.mathworks.com/help/matlab/ref/xline.html

load train
t = timetable(linspace(datetime(2020,1,1),datetime(2020,1,2),length(y))',y);
ipt = findchangepts(t.y,'MaxNumChanges',4,'Statistic','rms');
plot(t.Time,t.y)
title(sprintf('Number of changepoints = 4\nTotal log weighted dispersion = -33002.6521'));
xline(t.Time(ipt),'Color',[0.4660 0.6740 0.1880]);