Check if a set of coordinates are on a line
조회 수: 11 (최근 30일)
이전 댓글 표시
I have a set of coordinates, for example x = [0 0 0 0] y = [1 0.9 1.1 1] or x = [1 2 3 4] y = [1 4 6 7], and I want to know if they are almost on a line. I can say the first exemple does and the second doesn't.
I tried with polyarea checking if the area is small enough but it's hard to define the crossing area value regarding the size of the polygon and, moreover, it gives the wrong answer if the polygon crosses itself, like in the first example.
Thank you in advice.
댓글 수: 1
KALYAN ACHARJYA
2019년 9월 18일
@Guillaume sir, sorry, I missed it, I misundestood the question and considering on image (Horizantal or Vertical line)
Always Thanks
채택된 답변
Bruno Luong
2019년 9월 18일
편집: Bruno Luong
2019년 9월 18일
xy=[x(:)';y(:)'];
criteriatol = 0.01; % adjust to your need, smaller means stricter line test
s = svd(xy-mean(xy,2));
isline = max(s)*criteriatol>min(s)
Work isotropically (orientation independent, but also scaling, shifting independent), even with vertical line.
추가 답변 (1개)
Guillaume
2019년 9월 18일
Probably, the best way is to use polyfit (which does a least square fit) and look at the norm of the residuals. If it's small enough your points (tolerance is up to you) are on a line.
[~, pfit] = polyfit(x, y, 1); %least square fit of a line
if pfit.normr <= arbitrary_value
disp('is a line');
else
disp('not a line');
end
You may need to special case when all the x are (almost) all equal (vertical line) if that's an actual possibility.
댓글 수: 2
참고 항목
카테고리
Help Center 및 File Exchange에서 Computational Geometry에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!