Separate Drawing of Gaussian Mixture Model
I have a 1D data which need to be separated by two . So I used fitgmdist(data,2); and got mu sigma component proportion for each of the gaussian distribution. And here is the graph. (Gray : Data, Blue : psd of GMModel from fitgmdist) Until here, everything was okay. So, question. How can I separate those two gaussian distribution graph? I tried Using makedist('Normal') to create each gaussian distribution. Multiply by each component proportion Add two distribution up But somehow I wasn't able to get the same graph overlapping picture above. Probably I have the wrong concept of "Normalization" or "Gaussian Mixture Model". Any advise or site to lookup would be grateful. ------------------------------------------------------------ @Image Analyst: data uploaded. thanks for the advice I'll remember that next time :)
John Williams answered .
2025-11-20
You did something like this:
x = [randn(4000,1)/2; 5+2*randn(6000,1)]; f = fitgmdist(x,2); histogram(x,'Normalization','pdf') xgrid = linspace(-4,12,1001)'; hold on; plot(xgrid,pdf(f,xgrid),'r-'); hold off
You can duplicate the pdf values by doing something like this:
n1 = makedist('normal',f.mu(1),sqrt(f.Sigma(1)));
n2 = makedist('normal',f.mu(2),sqrt(f.Sigma(2)));
p = f.ComponentProportion;
y = p(1)*pdf(n1,xgrid) + p(2)*pdf(n2,xgrid);
hold on; plot(xgrid,y,'c--'); hold off
One thing to watch out for. In probability and statistics, it's common to write the standard deviation of a univariate normal distribution as the Greek letter sigma. But it's common to write the covariance matrix of a multivariate distribution as capital Sigma. So that's why I used sqrt(Sigma) to create the univariate distributions.