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From: Chris Spencer <chrisspen@gm...>  20100920 20:36:41

Hi, Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve to a set of data points? Regards, Chris 
From: Benjamin Root <ben.root@ou...>  20100920 21:11:44
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On Mon, Sep 20, 2010 at 3:36 PM, Chris Spencer <chrisspen@...> wrote: > Hi, > > Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve > to a set of data points? > > Regards, > Chris > > That question would probably be better asked on the scipyusers list. I believe there is something for that, but I am not familiar with it. Ben Root 
From: Gökhan Sever <gokhansever@gm...>  20100920 22:10:56
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On Mon, Sep 20, 2010 at 3:36 PM, Chris Spencer <chrisspen@...> wrote: > Hi, > > Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve > to a set of data points? > > Regards, > Chris > I am very curious to know how this is done. I have seen in many Cloud Condensation Nuclei (CCN) counter calibration experiments [e.g. Rose et. al. (2008)  p1156, fig2 http://www.atmoschemphys.net/8/1153/2008/acp811532008.html] people use sigmoidal fits. Never seen a code is shared so far or how it is obtained. from scipy.optimize import leastsq could be a good point to start. To me this fit is very likely a least square minimization problem. You have your tanh(x) or 1/(1+e^x) as a sigmoidal function, and you should find the points that will make the error minimal for a given discrete points/measurements. from scipy.optimize import curve_fit might be another way to approach.  Gökhan 
From: Gökhan Sever <gokhansever@gm...>  20100920 22:44:13
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On Mon, Sep 20, 2010 at 3:36 PM, Chris Spencer <chrisspen@...> wrote: > Hi, > > Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve > to a set of data points? > You could also experiment at zunzun.com. Choose 2D sigmoidal from the 2D function scroll list.  Gökhan 
From: Chris Spencer <chrisspen@gm...>  20100921 01:44:22

Thank you. I'll try investigating Scipy further. I've already tried applying some leastsquares code for Numpy (http://pingswept.org/2009/01/24/leastsquarespolynomialfittinginpython/) to my sigmoid data, but it only seems to fit parabolas. I had already encountered zunzun.com while Googling the problem. I'm not sure what to make of it, although it seems to be an online curvefitting service. Unfortunately, my usage requires the ability to run the process locally. Regards, Chris On Mon, Sep 20, 2010 at 6:35 PM, Gökhan Sever <gokhansever@...> wrote: > On Mon, Sep 20, 2010 at 3:36 PM, Chris Spencer <chrisspen@...> wrote: >> >> Hi, >> >> Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve >> to a set of data points? > > You could also experiment at zunzun.com. Choose 2D sigmoidal from the 2D > function scroll list. >  > Gökhan > 
From: Bartosz Telenczuk <b.telenczuk@bi...>  20100921 07:51:10

Hi, Scipy.optimize.leastsq finds a least square fit to an arbitrary function. Check the scipy cookbook example: http://www.scipy.org/Cookbook/FittingData Regards, Bartosz On 20.09.2010, at 22:36, Chris Spencer wrote: > Hi, > > Does Matplotlib/Numpy/Scipy contain the ability to fit a sigmoid curve > to a set of data points? > > Regards, > Chris > >  > Start uncovering the many advantages of virtual appliances > and start using them to simplify application deployment and > accelerate your shift to cloud computing. > http://p.sf.net/sfu/novellsfdev2dev > _______________________________________________ > Matplotlibusers mailing list > Matplotlibusers@... > https://lists.sourceforge.net/lists/listinfo/matplotlibusers Bartosz Telenczuk Institute for Theoretical Biology Humboldt University of Berlin Germany http://neuroscience.telenczuk.pl 
From: James Phillips <zunzun@zu...>  20100921 16:22:33

Chris Spencer <chrisspen@...> writes: > > I had already encountered zunzun.com while Googling the problem. I'm > not sure what to make of it, although it seems to be an online > curvefitting service. Unfortunately, my usage requires the ability to > run the process locally. The fitting source code for http://zunzun.com is freely available under a BSDstyle license on Google's source code repository at http://code.google.com/p/pythonequations/downloads/list and comes with many examples  so you *can* run it locally. James Phillips zunzun@... http://zunzun.com 
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