[ncl-talk] PDF and CDF with Weibull distribution

[Md. Jalal Uddin]

Thanks a lot!

On Mon, Apr 29, 2019 at 10:01 PM Dennis Shea <shea at ucar.edu> wrote:

> NCL is *not* a statistics package and ncl-talk is not an expert on
> assorted distributions.
> Please ask a statistician questions about the Weibull distribution.
> Other tools [*R*, Matlab, Python] may be a better option.
> For sure, *R* has multiple functions that may be useful.
> -------
> *http://www.ncl.ucar.edu/Document/Functions/Built-in/weibull.shtml*
> <http://www.ncl.ucar.edu/Document/Functions/Built-in/weibull.shtml>
>
> Please *carefully* read the documentation.
> Example one shows a comparison of NCL's and R's result.
> ---
>
> TRMM: [time | 733] x [latitude | 120] x [longitude | 100]
>
> From experience, daily TRMM has **MANY** 0 values.
> You *may* want to sett all 0 value to _FillValue
>
> TRMM = *where*(*ismissing*(TRMM),TRMM at _FillValue, TRMM)
>
> ; Weibull at each grid point
>
> wTRMM  = *weibull*(TRMM, False, 0)             ; wTRMM(*2*,120,100)
> wTRMM at long_name = "Weibull: Grid point: Shape, Scale"
> copy_VarCoords(TRMM(0,:,:), wTRMM(0,:,:))
>
> *printVarSummary*(wTRMM)
> *printMinMax*(wTRMM,0)
> *print*("---")
>
> ; Weibull over entire region
>
> WTRMM  = *weibull*(*ndtooned*(TRMM), False, 0)   ; WTRMM(*2*)
> WTRMM at long_name = "Weibull: All points: Shape, Scale"
> printVarSummary(WTRMM)
> print(WTRMM,0)
> print("---")
>
> =========================================
>
> opt = True opt at confidence = 0.90
>
> wTRMM  = *weibull*(TRMM, opt, 0 )             ; wTRMM(6,120,100)
> wTRMM at long_name = "Weibull: Grid point: Shape, Scale; ShapeLow, ShapeHigh, ScaleLow, ScaleHigh"
> copy_VarCoords(TRMM(0,:,:), wTRMM(0,:,:))
> *printVarSummary*(wTRMM)
> *printMinMax*(wTRMM,0)
> *print*("---")
>
>
> WTRMM  = *weibull*(*ndtooned*(TRMM), opt, 0)            ; WTRMM(*6*)
> WTRMM at long_name = "Weibull: All points: Shape, Scale; ShapeLow, ShapeHigh, ScaleLow, ScaleHigh"
> print(WTRMM,0)
> print("---")
>
> ==========================================
>
> *You* will have to calculate the CDF and PDF. NCL does not have functions to do this.
>
> Good Luck
>
>
> On Sat, Apr 27, 2019 at 9:19 PM Md. Jalal Uddin <dmjalal90 at gmail.com>
> wrote:
>
>> Hi all,
>>
>> I want to calculate PDF and CDF with Weibull distribution using shape 5
>> and scale 2 parameters. I found one function in NCL that calculate the
>> extreme value (
>> https://www.ncl.ucar.edu/Document/Functions/Ext_val/extval_weibull.shtml
>>  ).
>>
>> However, I don't want to calculate the extreme value. I would like to
>> produce a similar figure in the attached figure (adapted from Prat and
>> Nelson 2013a).
>>
>> Any suggestions would be appreciated.
>>
>> Variable: TRMM
>> Type: float
>> Total Size: 35184000 bytes
>>             8796000 values
>> Number of Dimensions: 3
>> Dimensions and sizes:   [time | 733] x [latitude | 120] x [longitude |
>> 100]
>> Coordinates:
>>             time: [   0..131112]
>>             latitude: [0.125..29.875]
>>             longitude: [75.125..99.875]
>> Number Of Attributes: 7
>>   long_name :   precipitation (mm/hr)
>>   _FillValue :  -9999.9
>>   missing_value :       -9999.9
>>
>>
>> Best regards,
>> Jalal
>>
>> --
>> *Md. Jalal Uddin*
>> MSc in Applied Meteorology (English Language)
>> Nanjing University of Information, Science and Technology, China
>> B.Sc. in Disaster Management (Hons.)
>> Patuakhali Science and Technology University, Bangladesh.
>> Cell: +8613260859092, +8801792052662
>> Web: www.dmjalal90.weebly.com
>> Facebook: jalal.hossen.39
>> LinkedIn: https://bd.linkedin.com/in/md-jalal-uddin-80a026b0
>> Twitter: dmjalal90
>> Skype: dmjalal90
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>>
>

-- 
*Md. Jalal Uddin*
MSc in Applied Meteorology (English Language)
Nanjing University of Information, Science and Technology, China
B.Sc. in Disaster Management (Hons.)
Patuakhali Science and Technology University, Bangladesh.
Cell: +8613260859092, +8801792052662
Web: www.dmjalal90.weebly.com
Facebook: jalal.hossen.39
LinkedIn: https://bd.linkedin.com/in/md-jalal-uddin-80a026b0
Twitter: dmjalal90
Skype: dmjalal90
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