[SciPy-user] skew Gaussian distribution
elton wang
ahala2000@yahoo....
Thu Aug 23 13:31:59 CDT 2007
I use R (http://cran.r-project.org/) for distribution
fitting. skewed-normal/skew-t or what ever
distributions. very ease to use.
I also have RDcom server/client
installed(http://sunsite.univie.ac.at/rcom/). So R can
be called in python as below (windows XP) (from
website above)
>>> from win32com.client import Dispatch
>>> sc=Dispatch("StatConnectorSrv.StatConnector")
>>> sc.Init("R")
>>> print(sc.Evaluate("2+2"))
4.0 # COMMENT- R can do arithmetic and can tell python
about it!
>>>
--- David Goldsmith <David.L.Goldsmith@noaa.gov>
wrote:
> Ah, then I may be able to help you in two ways.
> First, my Google search
> turned up:
>
> http://azzalini.stat.unipd.it/SN/
>
> Visit the "very brief account" link thereon, but
> also note on the main
> page the passage titled "A pioneer" which hints at a
> possible "physical"
> basis for these distributions in nature; I didn't
> dig any deeper than
> that, but it seems worthwhile to assess whether the
> family of
> distributions he is discussing might "properly"
> represent your
> experimental population.
>
> Second, I used to work for an Astronomer/Applied
> Optics Engineer, and
> was thus exposed, albeit superficially, to physical
> derivations of
> empirical optical particle count distributions; I
> didn't learn enough to
> help you, but he probably could - if you're
> interested, I can forward
> you his email, or if your reticent about making a
> "cold" contact, I can
> forward your email to him to see if he thinks he can
> help.
>
> DG
>
> Gary Pajer wrote:
> > On 8/23/07, *David Goldsmith*
> <David.L.Goldsmith@noaa.gov
> > <mailto:David.L.Goldsmith@noaa.gov>> wrote:
> >
> > Please educate me: what are a "skew" and
> "kurtotid"
> > Gaussians? (What I
> > learned: Gaussians are - by definition -
> devoid of any
> > higher-than-second moments; wouldn't
> (shouldn't) a "Gaussian" with
> > higher-than-second moments be called something
> else entirely?)
> >
> >
> > Exactly. So I could rephrase my question: what
> is the name of the
> > distribution that is similar to a normal
> distribution, but has a
> > variable amount of skewness? Or is such a
> distribution a special
> > case of one of the many distributions in scipy?
> >
> > I *think* the pdf of a "skew normal" should be
> proportional to
> > exp(-a*x**2 - b*x**3) but that comes from a quick
> google search.
> >
> > Better yet: what I'm trying to do is simulate the
> spectrum of an
> > optical emitter that I have. The spectrum is
> nearly normal, but it is
> > not symmetric. I'm looking for a model
> distribution. I started by
> > looking for something quick and dirty. If
> "quick" doesn't happen, I
> > might actually have to figure out if there is
> already a
> > theoretically-expected distribution for my case.
> But in the meantime,
> > quick and dirty still sounds good.
> >
> > That's the real question.
> >
> > thanks for helping me express what I want :)
> > -gary
> >
> >
> >
> > DG
> >
> > Gary Pajer wrote:
> > > Do any of the distributions in scipy.stats
> make a skew Gaussian?
> > > Ditto, a Gaussian with kurtosis?
> > >
> > > thanks,
> > > -gary
> > >
> >
>
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> > >
> > >
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