[R-sig-Geo] Gaussian transformation

[Carlo Innocenti]

Thank you for your answers.

In the meantime, I found the package RGeostats developed by Geosciences
Research Center of MINES ParisTech on http://rgeostats.free.fr and at the
moment I'm studying it.
It seems promising with 3D geostatistics capability and function for
gaussian anamorphosis transformation and back transformation.

Carlo




2015-04-29 15:11 GMT+02:00 Paulo Justiniano Ribeiro Jr <
paulojus at c3sl.ufpr.br>:

> Perhaps you can also look at the Box-Cox family of transformation for
>> which some cases such as log is a particular case
>>
>> You may look at MASS::boxcox()
>> and/or boxcox related functions in geoR
>>
>> If log works well you benefit from the results of log-normal kriging.
>>
>>
>
> Paulo Justiniano Ribeiro Jr
> LEG (Laboratorio de Estatistica e Geoinformacao)
> Universidade Federal do Parana
> Caixa Postal 19.081
> CEP 81.531-990
> Curitiba, PR  -  Brasil
> Tel: (+55) 41 3361 3573
> VOIP: (+55) (41) (3361 3600) 1053 1066
> Fax: (+55) 41 3361 3141
> e-mail: paulojus AT  ufpr  br
> http://www.leg.ufpr.br/~paulojus
>
>
> On Wed, 29 Apr 2015, Carlo Innocenti wrote:
>
>  Thank you Edzer.
>>
>> It works, but I need the back transformation as well.
>> What about the gaussian anamorphosis with hermite polynomials? I know that
>> is a method used to normalize the data before to apply the conditional
>> gaussian simulation.
>> There is a package in R to transform and back transform with this method?
>> Another method that is used in these cases should be the normal scores
>> transformation: is it implemented in some package?
>>
>> Carlo
>>
>>
>>
>>
>> 2015-04-28 22:32 GMT+02:00 Edzer Pebesma <edzer.pebesma at uni-muenster.de>:
>>
>>  one way is the rank transform:
>>>
>>> x = rgamma(100, 0.1)
>>> hist(x)
>>> y = qnorm((order(x)/(length(x) + 0.5)))
>>> qqnorm(y)
>>>
>>> but transforming your conditionally simulated values back will be
>>> tricky. And I'm not sure about the 0.5.
>>>
>>> On 04/28/2015 06:09 PM, Carlo Innocenti wrote:
>>> > I would like to perform a gaussian conditional simulation on a variable
>>> > that is highly skewed.
>>> > Could someone suggest me how to transform my variable in a gaussian
>>> > distribution?
>>> >
>>> > Thanks,
>>> > Carlo
>>> >
>>> >
>>>
>>> --
>>> Edzer Pebesma
>>> Institute for Geoinformatics (ifgi),  University of Münster,
>>> Heisenbergstraße 2, 48149 Münster, Germany; +49 251 83 33081
>>> Journal of Statistical Software:   http://www.jstatsoft.org/
>>> Computers & Geosciences:   http://elsevier.com/locate/cageo/
>>> Spatial Statistics Society http://www.spatialstatistics.info
>>>
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>>
>>>
>>
>> --
>>
>>
>> Carlo Innocenti, PhD
>>
>> ISPRA
>> Istituto Superiore per la Protezione e la Ricerca Ambientale
>> High Institute for Environmental Protection and Research
>>
>> Via Vitaliano Brancati, 60
>> 00144 Roma
>> Italy
>>
>> phone: +39 06 5007 4639
>> email: carlo.innocenti at isprambiente.it
>>
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>>
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>
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>


-- 


Carlo Innocenti, PhD

ISPRA
Istituto Superiore per la Protezione e la Ricerca Ambientale
High Institute for Environmental Protection and Research

Via Vitaliano Brancati, 60
00144 Roma
Italy

phone: +39 06 5007 4639
email: carlo.innocenti at isprambiente.it

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