[R-sig-Geo] Gaussian transformation

[Paulo Justiniano Ribeiro Jr]

> 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
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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
>>
>>
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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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