how to color the area under the line??

Question

ahmed allaheani 2016-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/316275-how-to-color-the-area-under-the-line

回答： Nirav Sharda 2016-12-13

采纳的回答： Nirav Sharda

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i am using polar coordinates to plot an antenna coverage area shape. i got the code as following:

and i got the result :

i just need help at [ how can i shad or color the area under the curve ????]

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Image Analyst 2016-12-10

It's not clear what area you're referring to. If you mean between the line and the center, then it seems that some points are "inside" 3 curves or 4 curves. So do you count that area 3 times or 4 times or just once?

ahmed allaheani 2016-12-11

yes I am referring to the area between the line and the center. i count it only once

thanx

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Answer 1

Nirav Sharda 2016-12-13

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https://ww2.mathworks.cn/matlabcentral/answers/316275-how-to-color-the-area-under-the-line#answer_247072

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You can use the patch function here. I picked up 2 adjacent points and the center and created a patch inside a for loop. Also I used 'polar' instead of 'polarplot', because patch cannot be used for polaraxes.

r = [-18,-23,-29,-30,-30,-27,-24,-22,-32,-32,-30,-30,-24,-22,-25,-15,-20,-22,-27];
theta = linspace(-180,180,length(r));
polar(theta,r);
[x y]= pol2cart(theta,r);
for i = 1:length(r)-1
    x1 = [x(i) x(i+1) 0];
    y1 = [y(i) y(i+1) 0];
    patch(x1,y1,'r','EdgeColor','none');
end
% This can be optional. I added this so that the numbers 10 and 20 are
% visible
alpha(.1);