How to remove few data points from a MATRIX
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Hello Everyone ,
I have a set of points which are stored in n*3 MATRIX. These are points from a sensor and at the starting and ending there is a lot of disturbance in the signal and I get points which are very close to each other. I have to remove these points. So I check the distance between points starting from the first point and whenever I get a point outside a user input radius I break the loop.
The problem is I want to make a new array of dimensions m*3 in which I have the first point of my Input array then next (x) points are removed and then i get the remaining points.
Can someone help me with this?
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Jan
el 23 de Nov. de 2012
I'm not sure if I understood the concept of your "points" correctly. But perhaops you want something like this:
X = cumsum(rand(1000, 3)); % Test data
keep = false(1000, 1);
radius = 0.7;
radius_2 = radius ^ 2; % Avoid the expensive SQRT
orig = X(1, :);
keep(1) = true;
for ii = 2:1000
dist_2 = sum((X(ii, :) - orig) .^ 2);
if dist_2 > radius_2
keep(ii) = true;
orig = X(ii, :);
end
end
CleanedX = X(keep, :);
3 comentarios
Jan
el 25 de Nov. de 2012
Perhaps you are right, I.A. (is the abbreviation ok? After all these years I still hesitate to call you like your profession). I thought this means the opposite: "... I get points which are very close to each other. I have to remove these points."
Image Analyst
el 25 de Nov. de 2012
You can call me IA - no problem. I read it as he had sensor points (3D coordinates as rows in his n*3 array) and the several rows at the top and bottom were from the sensor and they were good. The stretch in the middle were bad points "with a lot of disturbance" and he didn't want those points (rows). So he wanted to check which points were close to the very first point (which was assumed to be good), and keep those (perhaps extracted into a new array) and discard the rest. When he said "have the first point of my Input array then next (x) points are removed and then i get the remaining points." I took that to mean keep the first few good points at the beginning, remove the bad points in the middle, and keep the remaining good points at the end. But it's not totally clear and he should clarify.
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