Patch and fill functions are not shading area between confidence intervals in 2024a

I am trying to fill the area between two confidence intervals in Matlab 2024a. It is a depth-temperature chart where depth is Y and the confidence intervals are an upper and lower temperature bound in X. I have searched everything online, tried many things, and do not understand why the lines of the upper and lower bound will appear, but the area between the confidence intervals will not shade when calling both patch() and fill(). Here is a bit of my code:

clf;

plot(meanT, Depth, "r-", 'LineWidth', 2)

hold on

patch([Tlower; fliplr(Tupper)], [Depth; fliplr(Depth)], 'g')

Depth, meanT, Tlower, Tupper are all [nx1]. I have tried changing fliplr to flipud or just flip with no success. I have also tried transforming Tupper/Tlower to be sorted so they are smallest-to-largest and calling patch()/fill() on the sorted values. Same issue occurs. Any help to resolve this is much appreciated.

Answer 1

[Voss]

This will work regardless of the orientation of the vectors, i.e., whether each is a row or column vector:

patch([Tlower(:); flipud(Tupper(:))], [Depth(:); flipud(Depth(:))], 'g')

assuming Depth is sorted (either way).

Running an example with random data (note that you need to plot the patch before the mean line in order to see the mean line on top of the patch, or else use a patch with some transparency):

Depth = 1:10;
meanT = rand(10,1);
Tlower = meanT.'-1;
Tupper = meanT+1;

whos Depth *T* % some are row vectors and some are column vectors

  Name         Size            Bytes  Class     Attributes

  Depth        1x10               80  double              
  Tlower       1x10               80  double              
  Tupper      10x1                80  double              
  meanT       10x1                80  double              

figure
patch([Tlower(:); flipud(Tupper(:))], [Depth(:); flipud(Depth(:))], 'g')
hold on
plot(meanT, Depth, "r-", 'LineWidth', 2)

If this doesn't give the expected result, then please save your variables to a mat file and upload it here using the paperclip button.

[Olivia]

Hey Voss, thanks for the reply. I tried that and I'm still not able to get it to work! I attached a .mat file and a figure of what comes out when I execute this code:

load variables.mat

whos Depth *T*

  Name         Size            Bytes  Class     Attributes

  Depth       60x1               480  double              
  Tlower      60x1               480  double              
  Tupper      60x1               480  double              
  meanT       60x1               480  double              

figure
patch([Tlower(:); flipud(Tupper(:))], [Depth(:); flipud(Depth(:))], 'g')
hold on
plot(meanT, Depth, "r-", 'LineWidth', 2)
set(gca, 'YDir','reverse')

[Rik]

I'm on mobile so I can't do it for you, but you can select your code, click the code button (which will format your code as code), after which you can run the code. That will allow everyone to see the result directly in the thread.

[Olivia]

Just updated the post per your suggestion, thanks!

[Voss]

The problem is NaNs in the T variables. A patch doesn't render if it has NaNs in it, so those have to be removed when creating the patch.

load variables

% make versions without NaNs for plotting the patch
idx_nan = isnan(Tlower) | isnan(Tupper);
Tlower_plot = Tlower(~idx_nan);
Tupper_plot = Tupper(~idx_nan);
Depth_plot = Depth(~idx_nan);

figure
patch([Tlower_plot(:); flipud(Tupper_plot(:))], [Depth_plot(:); flipud(Depth_plot(:))], 'g')
hold on
plot(meanT, Depth, "r-", 'LineWidth', 2)
set(gca, 'YDir','reverse')

[Olivia]

This worked thank you for the solution!

[Voss]

You're welcome!