color region in the plot based on the values

Hi,

In the attached array, I need to color the region based on whenever A(:,2) is greater than 5. I tried yregion,seems this will work only in 2023.

[Dyuman Joshi]

Which version of MATLAB are you using?

If you want an output similar to what yregion provies, what is the upper limit for the region?

If it is not similar to that, what is the expected output? A visual example would be helpful.

[Dyuman Joshi]

You forgot to provide the end values -

Red color from 5 to what? Inf?

Similarly, green color from what to 5? -Inf?

And I suppose the x-limits should be the range of the x values i.e. A(:,1)?

Answer 1

[Star Strider]

Try this —

LD = load('matlab.mat');
A = LD.A

A = 12493×2

-5.3531 1.3833 -5.1375 1.5149 -5.1375 1.5471 -5.1375 1.6226 -5.1375 1.6774 -5.1375 1.3851 -5.1375 1.5581 -5.1375 1.5314 -4.9938 1.7729 -4.9938 1.5963

thrshld = 5;
Lv = A(:,2) > thrshld;

idx1 = find(Lv);
idx2 = idx1(diff([0; idx1]) == 1);
% [x1,x2] = bounds(idx2)
idx2 = min(idx2) : max(idx2);


figure
plot(A(:,1), A(:,2))
hold on
patch([A(idx2,1); flip(A(idx2,1))], [thrshld+zeros(size(A(idx2,2))); flip(A(idx2,2))], 'r', 'FaceAlpha',0.5, 'EdgeColor','none')
patch([A(idx2,1); flip(A(idx2,1))], [min(ylim)+zeros(size(A(idx2,2))); thrshld+zeros(size(A(idx2,2)))], 'g', 'FaceAlpha',0.5, 'EdgeColor','none')
hold off
grid

.

[Star Strider]

As always, my pleasure!

I was having problems getting the green area to work correctly.

Try this —

LD = load('matlab.mat');
A = LD.A

A = 12493×2

-5.3531 1.3833 -5.1375 1.5149 -5.1375 1.5471 -5.1375 1.6226 -5.1375 1.6774 -5.1375 1.3851 -5.1375 1.5581 -5.1375 1.5314 -4.9938 1.7729 -4.9938 1.5963

thrshld = 5;
Lv1 = A(:,2) > thrshld;

Lv2 = A(:,2) <= thrshld;

figure
plot(A(:,1), A(:,2), '.-')
hold on
patch([A(Lv1,1); flip(A(Lv1,1))], [thrshld+zeros(size(A(Lv1,2))); flip(A(Lv1,2))], 'r', 'FaceAlpha',0.5, 'EdgeColor','none')
patch([A(:,1); flip(A(:,1))], [min(ylim)*ones(size(A(:,2))); min([thrshld+zeros(size(A(:,2))) flip(A(:,2))],[],2)], 'g', 'FaceAlpha',0.5, 'EdgeColor','none')
hold off
grid

.

[Turbulence Analysis]

Perfect! Thanks again

[Star Strider]

As always, my pleasure!