Re: [Rd] Problem with fitdistr for gamma in R 2.2.0

From: P Ehlers <ehlers_at_math.ucalgary.ca>
Date: Thu 17 Nov 2005 - 21:14:38 GMT

I think the problem may lie with fitdistr(). Specifically, replacing the code in fitdistr.R (VR_7.2-20) (line 137 to end) with the code in VR_7.2-8 (line 92 to end) seems to handle

   fitdistr(otm, "gamma")

just fine. But I haven't done much testing.

Peter Ehlers

Peter Dalgaard wrote:
> P Ehlers <ehlers@math.ucalgary.ca> writes:
>
>

>>Gregor,
>>
>>  fitdistr(otm, "gamma", method="L-BFGS-B")
>>
>>works for me (on WinXP). Or you could specify "lower = 0".

>
>
> The really odd thing is that it even works with
>
>
>> fitdistr(otm, "gamma",lower=-Inf)

>
> shape rate
> 1.03081094 0.18924370
> (0.09055117) (0.02117350)
>
> or even
>
>
>> fitdistr(otm, "gamma",upper=Inf)

>
> shape rate
> 1.03081094 0.18924370
> (0.09055117) (0.02117350)
>
>
> Also
>
>
>> fitdistr(otm, "gamma",control=list(parscale=c(.1,.1)))

>
> shape rate
> 1.03079500 0.18923897
> (0.09055106) (0.02117363)
>
> and quite amusingly:
>
>
>
>> fitdistr(otm, "gamma",method="BFGS",lower=0)

>
> shape rate
> 1.03081096 0.18924371
> (0.09055118) (0.02117350)
> Warning message:
> bounds can only be used with method L-BFGS-B in: optim(x = c(0.059610966029577, 0.0591496321922168, 0.14, 0.18,
>
>> fitdistr(otm, "gamma",method="CG",lower=0)

>
> shape rate
> 1.03081096 0.18924371
> (0.09055118) (0.02117350)
> Warning message:
> bounds can only be used with method L-BFGS-B in: optim(x = c(0.059610966029577, 0.0591496321922168, 0.14, 0.18,
>
> whereas the same calls without the dysfunctional lower= gives the
> warning about `shape` needing to be positive.
>
> This probably all indicates that something inside optim() is broken.
>
>
>
>
>>I no longer have 2.1.0 running, so I don't know why this
>>wasn't needed in 2.1.0.
>>
>>"R version 2.2.0, 2005-10-24"
>>MASS version: 7.2-20
>>
>>-peter
>>
>>Gorjanc Gregor wrote:
>>
>>>Dear R developers,
>>>
>>>I have encountered strange behaviour of fitdistr for gamma in recent R
>>>build i.e. 2.2.0. I have attached the code for data at the end of this mail
>>>so you can reproduce the problem. In short, I am able to run fitdistr under
>>>2.1.0 without problems, while I get the following error under 2.2.0
>>>(Version 2.2.0 Patched (2005-11-15 r36348))
>>>
>>>
>>>
>>>>fitdistr(otm, "gamma")
>>>
>>>Error in densfun(x, parm[1], parm[2], ...) : 
>>>        'shape' must be strictly positive
>>>
>>>The results on 2.1.1 (Version 2.1.1 (2005-06-20)) are
>>>
>>>
>>>
>>>>fitdistr(otm, "gamma")
>>>
>>>    shape       rate  
>>>  1.030667   0.189177 
>>> (0.090537) (0.021166)
>>>
>>>Platform: Windows XP
>>>
>>>Thank you in advance for your effort on this remarkable tool!
>>>
>>>Here is the data for above problem/results:
>>>
>>>"otm" <-
>>>c(0.059610966029577, 0.0591496321922168, 0.14, 0.18, 0.24, 0.25, 
>>>0.270071982912719, 0.270758049933706, 0.269911804412492, 0.280138451903593, 
>>>0.279787947586738, 0.279429937571753, 0.3, 0.320746235495899, 
>>>0.319553311037365, 0.51, 0.54, 0.56, 0.6, 0.609812622915953, 
>>>0.609198293855879, 0.64, 0.69, 0.74, 0.76, 0.770972826186568, 
>>>0.769288654833566, 0.78, 0.789181584270671, 0.78991363293305, 
>>>0.8, 0.89, 0.900691718998831, 0.8991656800583, 0.92, 0.93, 0.94, 
>>>1.01, 1.02, 1.13, 1.18, 1.26, 1.29, 1.33, 1.42, 1.43, 1.47, 1.47940529614314, 
>>>1.47920716832764, 1.6, 1.61, 1.63, 1.68938231960637, 1.6894849291523, 
>>>1.82, 1.88088044053270, 1.8792804789003, 1.89, 1.92, 2, 2.04, 
>>>2.07, 2.12, 2.17, 2.18, 2.22, 2.23, 2.27, 2.28, 2.3, 2.32092240267433, 
>>>2.31912300181622, 2.38, 2.39, 2.43, 2.46, 2.51, 2.52, 2.55, 2.56, 
>>>2.61, 2.66091404781397, 2.6595832825806, 2.67, 2.7, 2.77, 2.8, 
>>>2.81, 2.86, 2.87, 2.93, 3.01, 3.05, 3.14, 3.15, 3.17, 3.18, 3.24, 
>>>3.26, 3.33, 3.44, 3.45, 3.52, 3.55, 3.63, 3.73, 3.9, 4, 4.01, 
>>>4.04, 4.13, 4.15934497380769, 4.16094719917513, 4.3, 4.33, 4.34, 
>>>4.66, 4.76, 4.82, 4.83, 4.89, 4.92, 5.06, 5.14, 5.16, 5.26, 5.31, 
>>>5.36, 5.48, 5.66, 5.79, 5.8, 5.85, 5.87, 5.92952534468565, 5.92962284128508, 
>>>6.04, 6.11, 6.13, 6.16, 6.19, 6.42, 6.66, 6.69, 7.11, 7.16, 7.29, 
>>>7.3, 7.31, 7.33, 7.72, 7.82, 7.87, 7.91, 8.01, 8.17, 8.45, 8.49, 
>>>8.73, 8.86, 8.95, 9, 9.05, 9.13, 9.22, 9.52, 9.82, 9.88, 9.91, 
>>>9.99, 10.03, 10.4, 10.59, 10.83, 11.06, 11.64, 11.85, 12.02, 
>>>12.4, 12.64, 12.96, 13.44, 14.06, 14.07, 14.37, 15.4, 15.6, 15.92, 
>>>16.23, 16.6, 16.97, 17.06, 17.8, 18.69, 18.73, 19.2, 19.51, 19.54, 
>>>20.57, 21.05, 22.23, 27.02)
>>>
>>>Lep pozdrav / With regards,
>>>    Gregor Gorjanc
>>>
>>>----------------------------------------------------------------------
>>>University of Ljubljana
>>>Biotechnical Faculty        URI: http://www.bfro.uni-lj.si/MR/ggorjan
>>>Zootechnical Department     mail: gregor.gorjanc <at> bfro.uni-lj.si
>>>Groblje 3                   tel: +386 (0)1 72 17 861
>>>SI-1230 Domzale             fax: +386 (0)1 72 17 888
>>>Slovenia, Europe
>>>----------------------------------------------------------------------
>>>"One must learn by doing the thing; for though you think you know it,
>>> you have no certainty until you try." Sophocles ~ 450 B.C.
>>>
>>>______________________________________________
>>>R-devel@r-project.org mailing list
>>>https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>>Peter Ehlers
>>University of Calgary
>>
>>______________________________________________
>>R-devel@r-project.org mailing list
>>https://stat.ethz.ch/mailman/listinfo/r-devel
>>

>
>
-- 
Peter Ehlers
Department of Mathematics and Statistics
University of Calgary, 2500 University Dr. NW

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Received on Fri Nov 18 08:22:05 2005

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