Using ALS algorithm for writing a code
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Is ALS algorithm supported by MATLAB R2019a. What is the best source of downloading the alogorithm and the reference to write the code for analysing spectral data?
回答（1 个）
Star Strider
2019-4-26
I’ve not run this, so I have no experience with it. It’s the only MATLAB code for the algorithm that I could find.
The slightly corrected version of the function:
function z = baseline(y, lambda, p)
% Estimate baseline with asymmetric least squares
m = length(y);
D = diff(speye(m), 2);w = ones(m, 1);
for it = 1:10
W = spdiags(w, 0, m, m);
C = chol(W + lambda * D' * D);
z = C \ (C' \ (w .* y));
w = p * (y > z) + (1 - p) * (y < z);
end
Also consider:
function z = baseline(y, lambda, p)
% Estimate baseline with asymmetric least squares
m = length(y);
D = diff(speye(m), 2);w = ones(m, 1);
for it = 1:10
W = spdiags(w, 0, m, m);
C = chol(W + lambda * (D' * D));
z = C \ (C' \ (w .* y));
w = p * (y > z) + (1 - p) * (y < z);
end
The documentation for the function is in the paper.
Experiment to get the result you want.
5 个评论
Csaba
2019-10-2
at the very beginning I would add:
if isrow(y)
y=y';
end
Timothy Loayza
2020-8-23
Thanks a lot, it works very well for Raman's spectras. (lambda = 100'000, p = 0.01)
BTW : I don't know who to cite for it as the link is not working anymore.
Star Strider
2020-8-23
Timothy Loayza — I actually saved it. I am attaching it here. (It was apparently open-access at the time, so I doubt that I am violating any copyright by posting it here.)
Also, with respect to Csaba’s comment, if you want to force it to be a column vector, just do this:
y(:)
.
Raimund
2025-11-4
移动：Star Strider
2025-11-4
Hi,
thanks. This implementation works great.
Best regards,
Raimund
Star Strider
2025-11-4
移动：Star Strider
2025-11-4
My pleasure!
A Vote would be appreciated!
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2019-4-26
2025-11-4
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