Generate a sector mask within a big matrix

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Ankit Labh 2019-12-11

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/496075-generate-a-sector-mask-within-a-big-matrix

评论： Ankit Labh 2019-12-11

采纳的回答： Looky

A sector mask is defined by distance and angle. Please see the image for clarification on mask.

I want to generate a 100 by 100 matrix where all the matrix element inside the mask is 1 otherwise 0.

Thanks.

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Looky 2019-12-11

Do you already have the coordinates as show in the image? Then just convert to polar using cart2pol and afterwards use some simple logic to check for radius and the angle.

Turlough Hughes 2019-12-11

Can you attach the matrix as a .mat

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Answer 1

Looky 2019-12-11

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/496075-generate-a-sector-mask-within-a-big-matrix#answer_405944

编辑：Looky 2019-12-11

在 MATLAB Online 中打开

Solution could look like this:

% Generate example coordinates
x=linspace(-1,1,100);
y=fliplr(linspace(-1,1,100));
[X,Y]=meshgrid(x,y);
% Parameters for sector
angle=10;
radiusIn=.8;
radiusOut=.2;
% Coordinates to polarcoordinates
[phi, rho]=cart2pol(X,Y);
phi=rad2deg(phi);
phi(phi<0)=-phi(phi<0);
% Generate mask
mask=rho>radiusOut & rho<radiusIn & phi>angle& phi<180-angle;
% Have a look at the mask
spy(mask);

For your problem you should exchange the first part of generating the X and Y values for your own coordinates. Otherwise the mask might not be centered the way your data is.