Plot extreme values on a time series

Hi, I have the attached plots. I would like to mark the maximum and minimum value with a marker and show the values on a legend.

Thanks

Answer 1

[Star Strider]

Use the max and min functions with two outputs to get the first instance of the maximum and minimum. Then use the second (index) output to find the value of time where it occurred:

[ymax,maxidx] = max(y);
[ymin,minidx] = min(y);

figure(1)
plot(time, y)
hold on
plot(time(maxidx), ymax, '^r')
plot(time(minidx), ymin, 'vr')
hold off
grid

If you have more than one values for the maximum or minimum, use the find function:

maxidx = find(y == max(y));

and the plot calls then change to:

plot(time(maxidx), y(maxidx), '^r')

and the same for the minima.

NOTE — This is UNTESTED CODE but should work.

[Fatemah Ebrahim]

How do you show these values (the corresponding time) on the legend?

Answer 2

[Peppe]

Lets say you have a timeserie output where in one column you have Time and in the other you have Data:1 then for finding the max you simply can do

maxPoint = max(x)

It looks through the Data column. Now check for the time idex that is the same as for Data column:

timeIndex = find(x.data == maxPoint);

Now check the time:

x.Time(timeIdex);

Then you plot them as previous comment.