How can I add noise to linear graph
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I have 100 sample points and I'm using y=mx+c to create 1d line and add gaussian noise using randn the attached graph is the result that I got when I tried the first code and when I try the second code I get straight line I think there is something wrong with my plot but I'm not sure where ?
code1
sample = 100;
x = linspace(-5,5);
y= 1.6 * x +6;
dataset = randn(sample,2);
figure
plot(dataset,y)
axis([-8 7])
code2
sample = 100;
x = linspace(-5,5);
y= 1.6 * x +6;
dataset = y*randn(sample,2);
figure
plot(dataset)
axis([-8 7]);
![](https://www.mathworks.com/matlabcentral/images/broken_image.png)
this is the result that I want to get
![](https://www.mathworks.com/matlabcentral/images/broken_image.png)
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jgg
am 21 Jan. 2016
Bearbeitet: jgg
am 21 Jan. 2016
You never added the random noise to your dataset:
sample = 100;
x = linspace(-5,5);
y= 1.6 * x +6;
r = randn(2,sample);
figure
plot(x,r(1,:)+y)
hold on
plot(x,r(2,:)+y)
The actual outcome value is y + r(i,:) not just y; you also are plotting it incorrectly before.
2 Kommentare
jgg
am 21 Jan. 2016
Yes. Let's code it up a little more clearly since you want to fit something too:
sample = 100;
x = linspace(-5,5);
y= 1.6 * x +6;
r = randn(2,sample);
y_noise = y + r(1,:);
X = [ones(1,length(x)); x];
beta = regress(y_noise',X');
y_fitted = beta(1) + x*beta(2);
figure
plot(x,y_noise)
hold on
plot(x,y_fitted)
This fits a linear regression curve to the noisy data using the regress function with an intercept. The coefficients are in beta.
If this answer solved your problem, please help others find it by accepting it.
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