Shade an area in a plot between two Y values

Dear MATLAB community,

I have a time series plot, and would like to shade specific regions in light grey (transparent).

The time series plot is an economic process, and I would like to shade times of recessions.

That is, I already have the values of the y-axis (the respective start date and end date of a recession), and I already have a nice plot, but I cannot figure out how to add these 'recession shadings'.

In short: I would like to shade an area in a time series plot, and the area is defined as:

X(:)              % all x
Y(y1,y2)          % between y1 and y2

Thank you!

Answer 1

[Star Strider]

See if this does what you want:

x = linspace(0, 10, 10);
y = randi(9, 1, 10);
ybars = [2 6];

figure(1)
hp = plot(x, y, 'bp');
hold on
patch([min(xlim) max(xlim) max(xlim) min(xlim)], [ybars(1) ybars(1), ybars(2) ybars(2)], [0.8 0.8 0.8])
plot(x, y, 'bp')
hold off
axis([0  10    0  10])

You will have to modifiy it to do what you want, but that should be straightforward. Note the repeated plot call to prevent the patch from hiding it.

[Christoph Meier]

My bad, I made a mistake!

I swapped X and Y:

Obviously, X is the t-axis, and Y is the value axis of my process.

Thus, I am looking for a way to shade two X values, for all Y.

Thank you Star Strider, sorry for the wrong question specs

[Star Strider]

Simple modification of my previous code:

x = linspace(0, 10, 10);
y = randi(9, 1, 10);
xbars = [2 6];

figure(1)
hp = plot(x, y, 'bp');
hold on
patch([xbars(1) xbars(1), xbars(2) xbars(2)], [min(xlim) max(xlim) max(xlim) min(xlim)], [0.8 0.8 0.8])
plot(x, y, 'bp')
hold off
axis([0  10    0  10])

Again, you will have to modify it to do what you want in your application, but the modifications should be relatively straightforward to do.

[Christoph Meier]

Thank you, star strider!

As always, I much appreciate your help!

[Star Strider]

And as always, my pleasure!

[jen Magnes]

Thank you! Very helpful!

[Star Strider]

As always, my pleasure!

[Afiq Azaibi]

In addition to Start Strider's solution, starting in R2023a you can use the xregion and yregion functions:

plot([datetime(2020, 1, 1), datetime(2023, 1, 1)], [1, 2]);
xregion(datetime(2021, 1, 1), datetime(2022, 1, 1));

Answer 2

[Narendra Sharma MadanLal Sharma]

Thanks a lot ,Star Strider!

[Star Strider]

My pleasure!

[Jonathan Bishop]

Didn't spend more than a minute on this so possibly there is more to it, but if using a legend, both the patch and the double call to plot will affect the current spot in the ordered list of plot colors. Set the patch handlevisibility to 'off' and use cla after the first plot, if you don't want to bother dealing with the color order in a more programmatic fashion.

Answer 3

[A K M Kamrul Hasan]

Hi,

This discussion is about the srea bounded by straight lines. However, is it possible to shade an area in Matlab plot bounded by straight lines and curved lines? (i.e like the attached image) ?

Regards,

Kamrul Hasan

[Star Strider]

Yes.

[A K M Kamrul Hasan]

May I know the necessary commands for that?

[Star Strider]

Just seeing this now.

Yes! It is definitely possible.

x = linspace(0, pi);
y = sin(x);
Pm = 0.5;
xPm = interp1(y(x<=pi/2), x(x<=pi/2), Pm)                                       % Calculate Interseection

xPm = 0.5237

deltam = interp1(y(x>=pi/2), x(x>=pi/2), Pm)                                    % Calculate Interseection

deltam = 2.6179

figure
plot(x, y)
Lv1 = (x>=pi/2) & (y>=Pm);                                                      % Logical Vector
Lv2 = (x>=xPm) & (x<=pi/2);                                                     % Logical Vector
patch([x(Lv1) flip(x(Lv1))], [ones(size(x(Lv1)))*Pm flip(y(Lv1))], 'r' )        % Call 'patch'
patch([x(Lv2) flip(x(Lv2))], [zeros(size(x(Lv2))) ones(size(y(Lv2)))*Pm], 'r')  % Call 'patch'
yline(Pm,'-k','P_m', 'LabelHorizontalAlignment','left', 'FontWeight','bold')
text(median(x(Lv2)), Pm/2, 'A_1', 'Horiz','center', 'Vert','top')
text(median(x(Lv1)), (max(y)+Pm)/2, 'A_2', 'Horiz','right', 'Vert','top')
hold on
plot([1 1]*deltam, [0 Pm], '--k')
hold off

It’s worth noting how ‘Lv’ is constructed. It combines the logical values where and to create the appropriate bounding region to fill with patch.

Add the other text calls to create text in the appropriate places. The x-axis location for has been calculated.

.