How can i fit a linear line to a scatter plot knowing the intercept?

Question

Joseph 2018-7-12

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410045-how-can-i-fit-a-linear-line-to-a-scatter-plot-knowing-the-intercept

回答： Star Strider 2018-7-12

Hi, I have an array lets say, E(500,2) and I want to fit a line to scatter plot of E (scatter(E(:,1), E(:,2))), but the intercept for this fit is known within the error. if i use polyfit(E(:,1),E(:,2),1), i cannot determine the intercept. is there any way that I can fit a linear line with a fixed intercept?

thanks in advance

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Answer 1

Star Strider 2018-7-12

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410045-how-can-i-fit-a-linear-line-to-a-scatter-plot-knowing-the-intercept#answer_328591

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See if this does what you want:

E = rand(500, 2);                                       % Create Data
x = E(:,1);                                             % Create Data
y = E(:,2);                                             % Create Data
intercept = 0.7;                                        % Create Data
B = x(:) \ (y(:)-intercept);                            % Estimate Parameters (Linear Model)
yfit = [x(:) ones(size(x(:)))]*[B; intercept];          % Fit Data
figure
plot(x, y, 'pg')
hold on
plot(x, yfit, '-r')
hold off