given that you have this line of code how do you count the number of points in each quadrant ?

Classical = pdist2(matrix_logdiff_nsample, mean(matrix_logdiff_nsample),'mahal');
p = size(matrix_logdiff_nsample,2);
chi2quantile = chi2inv(0.99,p);
[SFmcd, MFmcd, Fmcd, OutFmcd] = robustcov(matrix_logdiff_nsample);
plot(Classical, Fmcd, 'o')
line([chi2quantile, chi2quantile], [0, 120], 'color', 'r')
line([0, 80], [chi2quantile, chi2quantile], 'color', 'r')
hold on
plot(Classical(OutFmcd), Fmcd(OutFmcd), 'b*')
xlabel('Mahalanobis Distance')
ylabel('Robust Distance')
title('Distance Plot, Fast MCD method')

[jonas]

Duplicate

https://nl.mathworks.com/matlabcentral/answers/563549-given-that-you-have-the-code-below-how-do-you-write-a-code-to-count-the-number-of-points-in-each-q

[Adam Danz]

and very similar to

https://www.mathworks.com/matlabcentral/answers/563417-counting-using-statistics-tools#answer_464480

Answer 1

[Adam Danz]

@Afua Amoako Dadey

You just need to modify either of the two answers received for similar questions in the past (listed under your question).

To modify this answer, you just need to replace the centerPoint_x, centerPoint_y values with the coordinates you're using to define the quadrants.

Based on your image it would look something like,

centerPoint_x = 15;  % approximate guess based on image
centerPoint_y = 18;  % approximate guess based on image

[Afua Amoako Dadey]

Mr Adam is still not working

[Adam Danz]

Could you share your updated code and explain what's not working?

More detail needed. Are you getting an error? Are the results incorrect?

[Afua Amoako Dadey]

ok let me share

Classical = pdist2(matrix_logdiff_nsample, mean(matrix_logdiff_nsample),'mahal');
p = size(matrix_logdiff_nsample,2);
chi2quantile = chi2inv(0.99,p);
[SFmcd, MFmcd, Fmcd, OutFmcd] = robustcov(matrix_logdiff_nsample);
plot(Classical, Fmcd, 'o')
line([chi2quantile, chi2quantile], [0, 120], 'color', 'r')
line([0, 80], [chi2quantile, chi2quantile], 'color', 'r')
hold on
plot(Classical(OutFmcd), Fmcd(OutFmcd), 'b*')
xlabel('Mahalanobis Distance')
ylabel('Robust Distance')
title('Distance Plot, Fast MCD method')
centerPoint_y = 18;
centerPoint_x = 15;
 centerPoint_x = min(xlim) + range(xlim)/2; 
centerPoint_y = min(ylim) + range(ylim)/2; % Same thing as above but with ylim
 quad1 = x >= centerPoint_x & y >= centerPoint_y; 
 quad2 = x < centerPOint_x & y >= centerPoint_y; 
% %quad3 = % fill in....
% %quad4 = % file in....
% % Points that are in Quad1 are 
 x(quad1), y(quad1)
counts = accumarray([1+(matrix_logdiff_nsample(:)>=mean(matrix_logdiff_nsample)), 1+(matrix_logdiff_nsample(:)>=mean(matrix_logdiff_nsample))], 1, [2 2]);

[Afua Amoako Dadey]

This is the error message

[Adam Danz]

You need to exchange "x" and "Y" with whatever values you're using to define the center point. Don't just copy-paste without doing the thinking.