Shade standard deviation for time series

Hi!

I'm trying to shade the std (daily_std) for mean sst (daily_average).

I've seen similar questions, but those codes don't work for me.

My x-axis is one year of date times. My y axis is the mean of sst.

I've done the following code:

figure
curve1=daily_average(:,1)+daily_std(:,1); %only column 1 because every column is one different location
curve2=daily_average(:,1)-daily_std(:,1); 
plot(date,curve1,'r')
hold on
plot(date,curve2,'r')
hold on
date2 = [date, fliplr(date)];
inBetween = [curve1, fliplr(curve2)];
fill(date2, inBetween, 'g');
hold on;
plot(date, daily_average(:,1));

However, I obtain the following result:

Any idea?

Thank you very much

Answer 1

[Star Strider]

I cannot run your code, so I cannot test this.

However, fill may not be appropriate here. See if using patch instead does shat you want:

patch(date2, inBetween, 'g');

Your curtrent syntax will work for patch, so no other changes are necessary.

[JAIME DIEGO RICO]

But my vector of dates is in date format, so I receive the following error:

"Non-numeric data is not supported in 'patch'"

However, I've tried datenum(date2) but I receive the same message

[JAIME DIEGO RICO]

N=1:366;
date=datetime(2020,1,N); 
date=transpose(date);
daily_average=table2array(daily_average);
daily_std=table2array(daily_std);

figure
curve1=daily_average(:,1)+daily_std(:,1); %above curve
curve2=daily_average(:,1)-daily_std(:,1); %below curve
plot(date,curve1,'r')
hold on
plot(date,curve2,'r')
hold on
date2 = [date, fliplr(date)];
inBetween = [curve1, fliplr(curve2)];
patch(date2, inBetween, 'g');
% fill(date2, inBetween, 'g');
hold on;
plot(date, daily_average(:,1));

[Star Strider]

The only option appears to be to convert the datetime array to date numbers for the plot, then use patch.

Example —

dt = datetime('now')+calmonths(1:10);
dn = datenum(dt);
upper = rand(1,10)+2;
lower = rand(1,10);

figure
patch([dn fliplr(dn)], [upper fliplr(lower)], 'g')
datetick('x', 'mmm', 'keepticks','keeplimits')

EDIT — (10 Jul 2020 at 17:39)

This works, and produces the correct result with datetime vectors with my code:

figure
fill([dt, fliplr(dt)], [upper, fliplr(lower)].', 'g')
grid

so with respect to your code, try this:

fill(date2, inBetween.', 'g');

I rarely use fill, preferring patch, however it seems that leaving the first argument (independent variable vector) as a row vector and transposing the second argument (dependent variable vector) to a column vector will do what you want with fill. This is not in the documentation (at least I cannot find any reference to it), and simply required a bit of experimentation for me to discover it.

It produces the same result as the patch call with a datenum vector, without the inconvenience of having to convert the datetime vector to datenum.

.

[JAIME DIEGO RICO]

Thank you very much!!!! It worked!

[Star Strider]

As always, my pleasure!