Fill area between plot and the 0-line?

Hi,

I want to plot some data to show a difference to a reference value and i want that the curve above zero gets filled red and the area of the plot below zero gets filled with blue.

How do i do that?

Answer 1

[Akira Agata]

How about using area function?

The following is an example:

% Sample data
x = linspace(0,4*pi,1000);
y = sin(x);

% Extract positive and negative part
yp = (y + abs(y))/2;
yn = (y - abs(y))/2;

% Plot the data using area function
figure
area(x,yp,'FaceColor','r')
hold on
area(x,yn,'FaceColor','b')

[Julozert]

thank you very much

[Harshit]

ni chal ra

Answer 2

[the cyclist]

You can use either the fill or patch command. See the examples there for guidance.

[Julozert]

How do i use fill so that my positive data gets red and my negative data gets blue?

[the cyclist]

The way I would do it is to use your data points to define polygons that are above zero, and polygons that are below zero, and then use patch or fill, to fill them in.

[Julozert]

How can i use my data points to define polygons?

Answer 3

[Image Analyst]

For a more general situation, see the FAQ: https://matlab.fandom.com/wiki/FAQ#How_do_I_shade_the_region_between_two_curves.3F