How to count points outside the bound in scatter plot?

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Mahesh
Mahesh 2014-9-15
评论： Mahesh 2014-9-15
Dear all, I would like to count the points outside the bands as shown
in blue line which is 10% band in both side. The code is like this
ndata = length(data);
X = linspace(0, 1, ndata);%ndata is number of point
x = data/max(data); % data is normalized to 1
y = dy/max(dy);
xL = linspace(0.1,1, ndata); xL = xL(:); % lower line of band
yL = linspace(0,0.9, ndata); yL = yL(:);
xU = linspace(0,0.9, ndata); xU = xU(:);
yU = linspace(0.1,1, ndata); yU = yU(:);
hold on
plot(x, y, '.k')
plot(X, X, '-k'); X = X(:); % 45 degree angled line
plot(xL, yL, '-B'); % lower line of band
plot(xU, yU, '-B'); % upperline of band
pnts = [x y];
d1 = sqrt((x-X).^2+(y-X).^2); % calculation of distance between points
idout = find(d1>0.10); % here is the 10% band width and finding distance greater than 0.1
xOut = x(idout);
yOut = y(idout);
plot(xOut, yOut, '.r'); Want to display points outside the band in red
hold off
However I got something like this
</matlabcentral/answers/uploaded_files/18174/After.png> this is not the correct one. I think there is some algorithm problem or problem in handling code. Could any one help me in this regard. In fact, I just want the number of points oun side the band rather than plot. Plot is just the confirming.
Thanks in advance.

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采纳的回答

Michael Haderlein
Michael Haderlein 2014-9-15
I'm not exactly sure what's going on here (the link to your file does not work). However, if you want all data outside the lower/upper lines to be marked, you don't need some square root.
upperlim=y>x+0.1;
lowerlim=y<x-0.1;
plot(x(upperlim),y(upperlim),'ro')
plot(x(lowerlim),y(lowerlim),'co')
fprintf(1,'Data below limits: %d; data above limits: %d',sum(lowerlim),sum(upperlim))
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Mahesh
Mahesh 2014-9-15
As you suggested I got like this
which is also not correct the code is like this
idU = y > X+0.1;
idL = y > X-0.1;
plot(x(idU), y(idU), '.b')
plot(x(idL), y(idL), '.r')
I am not sure why.
Mahesh
Mahesh 2014-9-15
even with such code
idU = x > X+0.1 & y > X+0.1;
idL = x < X-0.1 & y > X-0.1;
does it make sense please?

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