Hello,
Does somebody know if there are Scilab functions capable of replacing
outliers via some local robust fitting in 2D, i.e., that smooths
experimental data z=f(x,y) and is immune to strong outliers.
PS: CASCI in Atoms has a lowess function which does this via local robust
linear fitting but f
Hello Rafael,
Le 04/03/2013 04:36, Rafael Guerra a écrit :
.../...
Does somebody know if there are Scilab functions capable of replacing
outliers via some local robust fitting in 2D, i.e., that smooths
experimental data z=f(x,y) and is immune to strong outliers.
2D smoothing is frequently perfo
Hello,
De la part de Rafael Guerra
Envoyé : lundi 4 mars 2013 04:37
> Does somebody know if there are Scilab functions
> [...] that smooths
> experimental data z=f(x,y) and is immune to strong outliers.
imho, the problem with smoothing and outliers is that
the definition of a outlier depends on
Le 04/03/2013 13:23, Dang, Christophe a écrit :
.../...
I personally would try Fourier filtering:
a strong outlier means a steep slope
and therefore correspond to a high frequency.
Thus fft2, set high frequencies to 0
(with possibly a smooth transition),
then inverse fft2 -- ifft2 does not exis
Hello,
Replacing the squared L2 norm by the L1 norm in the linear regression
gives a good robustness to outliers (cf. Donoho and al. papers). The
problem is then non differentiable but you can implement it by
iteratively reweighting the classical L2 method (IRLS method), or by
writing an equi
.
Regards,
Rafael
-Original Message-
From: users-boun...@lists.scilab.org [mailto:users-boun...@lists.scilab.org]
On Behalf Of Stéphane Mottelet
Sent: Monday, March 04, 2013 10:14 AM
To: users@lists.scilab.org
Subject: Re: [Scilab-users] Surface smoothing in Scilab, immune to outliers
cilab.org
Subject: Re: [Scilab-users] Surface smoothing in Scilab, immune to outliers
Hello,
Replacing the squared L2 norm by the L1 norm in the linear regression gives
a good robustness to outliers (cf. Donoho and al. papers). The problem is
then non differentiable but you can implement it by iterativ
Hi Rafael,
You can try to use lsq_splin along the axes x and y.
It seems to work on the following example:
x = %pi * [-1:0.05:1]';
z = sin(x)*cos(x)';
f = gcf();
f.color_map = jetcolormap(32);
subplot(131);
xtitle("Exact values");
plot3d(x, x, z, 70, 70);
e=gce();
e.color_flag = 1;
z = z + 0.5
users-boun...@lists.scilab.org [mailto:users-boun...@lists.scilab.org]
On Behalf Of Stéphane Mottelet
Sent: Monday, March 04, 2013 3:06 PM
To: users@lists.scilab.org
Subject: Re: [Scilab-users] Surface smoothing in Scilab, immune to outliers
Hello,
I have written a little script making the comparison
...@lists.scilab.org]
On Behalf Of Calixte Denizet
Sent: Monday, March 04, 2013 4:01 PM
To: users@lists.scilab.org
Subject: Re: [Scilab-users] Surface smoothing in Scilab, immune to outliers
Hi Rafael,
You can try to use lsq_splin along the axes x and y.
It seems to work on the following example:
x
b.org
[mailto:users-boun...@lists.scilab.org] On Behalf Of Calixte Denizet
Sent: Monday, March 04, 2013 4:01 PM
To: users@lists.scilab.org
Subject: Re: [Scilab-users] Surface smoothing in Scilab, immune to
outliers
Hi Rafael,
You can try to use lsq_splin along the axes x and y.
It seems to work o
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