R help - Feb 2012 - help error: In dweibull(x, shape, scale, log) : NaNs produzidos

Guys,
I'm having an error when I use the command:
library(MASS)> dados<-read.table("inverno.txt",header=FALSE)>
vento50<-fitdistr(dados[[1]],densfun="weibull")Mensagens de aviso
perdidas:1: In dweibull(x, shape, scale, log) : NaNs produzidos2: In dweibull(x,
shape, scale, log) : NaNs produzidos3: In dweibull(x, shape, scale, log) : NaNs
produzidos4: In dweibull(x, shape, scale, log) : NaNs produzidos5: In
dweibull(x, shape, scale, log) : NaNs produzidos6: In dweibull(x, shape, scale,
log) : NaNs produzidos> vento50     shape        scale     0.61473436  
2.43536064  (0.01895222) (0.13202750)

Can someone help??
Regards!
 		 	   		  
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Vanúcia SchumacherCurso de graduação em meteorologia - UFPELBolsista do Programa
de Educação Tutorial - PET

From: vanucia-schumacher@hotmail.com
To: r-help@r-project.org
Subject: help  error: In dweibull(x, shape, scale, log) : NaNs produzidos
Date: Tue, 21 Feb 2012 14:24:02 +0000







Guys,
I'm having an error when I use the command:
library(MASS)> dados<-read.table("inverno.txt",header=FALSE)>
vento50<-fitdistr(dados[[1]],densfun="weibull")Mensagens de aviso
perdidas:1: In dweibull(x, shape, scale, log) : NaNs produzidos2: In dweibull(x,
shape, scale, log) : NaNs produzidos3: In dweibull(x, shape, scale, log) : NaNs
produzidos4: In dweibull(x, shape, scale, log) : NaNs produzidos5: In
dweibull(x, shape, scale, log) : NaNs produzidos6: In dweibull(x, shape, scale,
log) : NaNs produzidos> vento50     shape        scale     0.61473436  
2.43536064  (0.01895222) (0.13202750)

Can someone help??
Regards!
 		 	   		   		 	   		  
	[[alternative HTML version deleted]]

On Feb 21, 2012, at 9:24 AM, Van?cia Schumacher wrote:
>
> Guys,
> I'm having an error when I use the command:
> library(MASS)>
dados<-read.table("inverno.txt",header=FALSE)>
> vento50<-fitdistr(dados[[1]],densfun="weibull")Mensagens de
aviso
> perdidas:1: In dweibull(x, shape, scale, log) : NaNs produzidos2: In  
> dweibull(x, shape, scale, log) : NaNs produzidos3: In dweibull(x,  
> shape, scale, log) : NaNs produzidos4: In dweibull(x, shape, scale,  
> log) : NaNs produzidos5: In dweibull(x, shape, scale, log) : NaNs  
> produzidos6: In dweibull(x, shape, scale, log) : NaNs produzidos>  
> vento50     shape        scale     0.61473436   2.43536064   
> (0.01895222) (0.13202750)
>
It's not an error, it's only a warning, at least to the level of my  
ability to read Spanish.

It suggests you managed to send negative or infinite numbers to  
dweibull, a distribution which only supports values when given  
positive, finite numbers. Look at your data more closely.

And learn to post in plain text. HTML does a poor job of communication.

-- 
David Winsemius, MD
West Hartford, CT

On Feb 21, 2012, at 16:36 , David Winsemius wrote:
> It suggests you managed to send negative or infinite numbers to dweibull, a
distribution which only supports values when given positive, finite numbers.
Look at your data more closely.
Zeros are a common cause, too. For a < 1 (the shape parameter), the Weibull
density has a singularity at zero, and fitdistr() is not tolerant of
observations rounded to zero in such cases.

-- 
Peter Dalgaard, Professor
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

On Feb 21, 2012, at 11:43 AM, peter dalgaard wrote:
>
> On Feb 21, 2012, at 16:36 , David Winsemius wrote:
>
>> It suggests you managed to send negative or infinite numbers to  
>> dweibull, a distribution which only supports values when given  
>> positive, finite numbers. Look at your data more closely.
>
> Zeros are a common cause, too. For a < 1 (the shape parameter), the  
> Weibull density has a singularity at zero, and fitdistr() is not  
> tolerant of observations rounded to zero in such cases.
And that may be more correct than my guess. I see that the estimate  
for the shape parameter  from fitdistr is less than 1 and was  
surprised that dweibull(-1, 2,2) does give a returned value of 0.

 >  dweibull(-.1, 0.61473436, 2.43536064 )
[1] 0
 >  dweibull(0, 0.61473436, 2.43536064 )
[1] Inf
 >  dweibull(0, 1.61473436, 2.43536064 )
[1] 0

-- 
David Winsemius, MD
West Hartford, CT

Hi,
then, If I replace the midpoint 0.0025 average values equal to 0there won't
be prejudice in the results?Would then be the best thing to do?

regards,


> Subject: Re: [R] help  error: In dweibull(x, shape, scale, log) : NaNs
produzidos
> From: pdalgd@gmail.com
> Date: Tue, 21 Feb 2012 18:55:51 +0100
> To: vanucia-schumacher@hotmail.com
> 
> 
> On Feb 21, 2012, at 18:34 , Vanúcia Schumacher wrote:
> 
> > Thank's,
> > 
> > but then I could simply round off my data which are equal to zero to
0.00001?
> 
> Something like that. I'd maybe try something a little more carefully
considered. E.g. if your data are rounded to two decimal figures, the
"zeros" represent values of x with
> 
>  0 < x < 0.005 
> 
> since anything bigger would be rounded to 0.01. So replace with the
interval midpoint of  0.0025.
> 
> (One can do better by modifying the likelihood, but then you essentially
have to rewrite fitdistr().)
> 
> > 
> > Att,
> > 
> > Vanúcia Schumacher
> > Curso de graduação em meteorologia - UFPEL
> > Bolsista do Programa de Educação Tutorial - PET
> > 
> > 
> > > Subject: Re: [R] help error: In dweibull(x, shape, scale, log) :
NaNs produzidos
> > > From: pdalgd@gmail.com
> > > Date: Tue, 21 Feb 2012 17:43:07 +0100
> > > CC: vanucia-schumacher@hotmail.com; r-help@r-project.org
> > > To: dwinsemius@comcast.net
> > > 
> > > 
> > > On Feb 21, 2012, at 16:36 , David Winsemius wrote:
> > > 
> > > > It suggests you managed to send negative or infinite numbers
to dweibull, a distribution which only supports values when given positive,
finite numbers. Look at your data more closely.
> > > 
> > > Zeros are a common cause, too. For a < 1 (the shape
parameter), the Weibull density has a singularity at zero, and fitdistr() is not
tolerant of observations rounded to zero in such cases.
> > > 
> > > -- 
> > > Peter Dalgaard, Professor
> > > Center for Statistics, Copenhagen Business School
> > > Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> > > Phone: (+45)38153501
> > > Email: pd.mes@cbs.dk Priv: PDalgd@gmail.com
> > > 
> 
> -- 
> Peter Dalgaard, Professor
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Email: pd.mes@cbs.dk  Priv: PDalgd@gmail.com
> 
 		 	   		  
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