Generate a sector mask within a big matrix

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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.
MASK.png
Thanks.
  2 Comments
Looky
Looky on 11 Dec 2019
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
Turlough Hughes on 11 Dec 2019
Can you attach the matrix as a .mat

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Accepted Answer

Looky
Looky on 11 Dec 2019
Edited: Looky on 11 Dec 2019
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.
  1 Comment
Ankit Labh
Ankit Labh on 11 Dec 2019
Dear Looky,
Many thanks for your answer. It worked. I got many new ideas for other questions.
best regards,
Ankit

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