[ncl-talk] Coefficient_of Divergence
Dennis Shea
shea at ucar.edu
Thu Nov 9 14:50:56 MST 2017
[1] I do not have the file:
maiactaotE.h00v02.20010040635-20011550640.nc
[2] where: See the 'Caveat' in the documentation
https://www.ncl.ucar.edu/Document/Functions/Built-in/where.shtml
*CoD = 1. / where(x2.ne.0, x1/x2, x2 at _FillValue) ; it can be divisible
by 0 *
should be
*CoD = (x1 / where(x2.ne.0, x2, x2 at _FillValue))^2 *
[3] I used a file with only a few time steps. See attached
On Wed, Nov 8, 2017 at 11:05 PM, Kunal Bali <kunal.bali9 at gmail.com> wrote:
>
> when I try the attached script (plot1.ncl) for large time steps say 442
> then
> it shows an error
>
>
>
> *fatal:divide: Division by 0, Can't continuefatal:Div: operator failed,
> can't continuefatal:["Execute.c":8640]:Execute: Error occurred at or near
> line 120 in file plot.ncl*
>
> *120 line is *
> CoD1 = ((DATA_SINGLE_3D - data_subset)/(DATA_SINGLE_3D + data_subset))^2
>
> So I separated this line to
> x1 = (DATA_SINGLE_3D - data_subset)
> x2 = (DATA_SINGLE_3D + data_subset)
>
> and then tried
>
>
> *CoD = 1. / where(x2.ne.0, x1/x2, x2 at _FillValue) ; it can be divisible
> by 0 CoD1 = (CoD)^2*
> printVarSummary(CoD1)
> printMinMax(CoD1, 0)
>
>
> But, still showing the same error
>
>
>
> *fatal:divide: Division by 0, Can't continuefatal:Div: operator failed,
> can't continuefatal:["Execute.c":8640]:Execute: Error occurred at or near
> line 120 in file plot.ncl*
>
>
> regards
> Kunal Bali
>
>
>
>
>
>
> On Wed, Nov 8, 2017 at 10:56 AM, Kunal Bali <kunal.bali9 at gmail.com> wrote:
>
>> I followed your instruction, But now CoD1 and CoD2 values are showing the
>> same values, which is incorrect? and because of this values of the square
>> root of CoD2 is not correct.
>>
>>
>> ;-----calculation of coefficient of divergence
>> CoD1 = ((DATA_SINGLE_3D - data_subset)/(DATA_SINGLE_3D+ data_subset))^2
>> printVarSummary(CoD1)
>> printMinMax(CoD1, 0)
>>
>> CoD1 at _FillValue = -28672
>> CoD2 = dim_avg_n_Wrap(CoD1, 0) ; (nlat,mlon)
>> printVarSummary(CoD2)
>> printMinMax(CoD2,0)
>>
>> CoD3 = sqrt(CoD2)
>> printVarSummary(CoD3)
>> printMinMax(CoD3, 0)
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> *Variable: CoD1Type: floatTotal Size: 7824960 bytes 1956240
>> valuesNumber of Dimensions: 3Dimensions and sizes: [3] x [660] x
>> [988]Coordinates: Number Of Attributes: 1 _FillValue : -28672(0)
>> min=0 max=0.961394Variable: CoD2Type: floatTotal Size: 2608320
>> bytes 652080 valuesNumber of Dimensions: 2Dimensions and
>> sizes: [660] x [988]Coordinates: Number Of Attributes: 2 _FillValue
>> : -28672 average_op_ncl : dim_avg_n function was applied(0)
>> min=0 max=0.961394Variable: CoD3Type: floatTotal Size: 2608320
>> bytes 652080 valuesNumber of Dimensions: 2Dimensions and
>> sizes: [660] x [988]Coordinates: Number Of Attributes: 1 _FillValue
>> : -28672(0) min=0 max=0.980507*
>>
>>
>>
>> regsrds
>> Kunal Bali
>>
>>
>>
>>
>>
>>
>> On Wed, Nov 8, 2017 at 3:55 AM, Dennis Shea <shea at ucar.edu> wrote:
>>
>>>
>>> *Variable: CoD1*
>>> *Dimensions and sizes: [3] x [660] x [988]*
>>> *(0) min=0 max=0.961394*
>>>
>>>
>>> step 2:
>>>
>>> CoD2 = sum(CoD1)/3 <=== No!
>>> printVarSummary(CoD2)
>>> printMinMax(CoD2, 0)
>>>
>>> https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_
>>> avg_n_Wrap.shtml
>>>
>>> CoD2 = dim_avg_n_Wrap(CoD1, 0) ; (nlat,mlon)
>>> printVarSummary(CoD2)
>>> printMinMax(CoD2,0)
>>>
>>> ===
>>> If you still have large numbers, the find one grid point where a large
>>> number occurs, then print the values.
>>>
>>> print(CoD1(:,nn,mm)) ; print series where large numbers occur
>>> (indices: nn,mm)
>>>
>>> See documentation for
>>> https://www.ncl.ucar.edu/Document/Functions/Built-in/ind.shtml
>>> https://www.ncl.ucar.edu/Document/Functions/Built-in/ind_res
>>> olve.shtml
>>> See Examples 2 & 3
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Nov 7, 2017 at 1:32 PM, Kunal Bali <kunal.bali9 at gmail.com>
>>> wrote:
>>>
>>>> Thanks for suggesting this.
>>>>
>>>> Actually, I am trying to calculate the COD at each grid cell.
>>>>
>>>> So as you suggested
>>>>
>>>>
>>>> *DATA_SINGLE_3D = conform(data_subset, data_single, 0) ; it worked*
>>>>
>>>>
>>>>
>>>> *Variable: DATA_SINGLE_3DType: floatTotal Size: 7824960 bytes
>>>> 1956240 valuesNumber of Dimensions: 3Dimensions and sizes: [3] x [660] x
>>>> [988]Coordinates: Number Of Attributes: 1 _FillValue : -28672*
>>>> step 1:
>>>> CoD1 = ((DATA_SINGLE_3D - data_subset)/(DATA_SINGLE_3D+ data_subset))^2
>>>> printVarSummary(CoD1)
>>>> printMinMax(CoD1, 0)
>>>>
>>>> *Variable: CoD1*
>>>> *Type: float*
>>>> *Total Size: 7824960 bytes*
>>>> * 1956240 values*
>>>> *Number of Dimensions: 3*
>>>> *Dimensions and sizes: [3] x [660] x [988]*
>>>> *Coordinates: *
>>>> *Number Of Attributes: 1*
>>>> * _FillValue : -28672*
>>>> *(0) min=0 max=0.961394*
>>>>
>>>>
>>>> step 2:
>>>>
>>>> CoD2 = sum(CoD1)/3
>>>> printVarSummary(CoD2)
>>>> printMinMax(CoD2, 0)
>>>>
>>>> *Variable: CoD2*
>>>> *Type: float*
>>>> *Total Size: 4 bytes*
>>>> * 1 values*
>>>> *Number of Dimensions: 1*
>>>> *Dimensions and sizes: [1]*
>>>> *Coordinates: *
>>>> *(0) min=20691.8 max=20691.8 --------> values are very
>>>> high? and also it's not giving at each grid cell, because of that I can't
>>>> calculate the sqrt in the next step*
>>>>
>>>>
>>>> step 3:
>>>>
>>>> CoD3 = sqrt(CoD2)
>>>> printVarSummary(CoD3)
>>>> printMinMax(CoD2, 0)
>>>>
>>>>
>>>> The final values are coming very high. It should be less than 0.3 at
>>>> each grid cell.
>>>>
>>>> regards
>>>> Kunal Bali
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, Nov 8, 2017 at 1:18 AM, Dennis Shea <shea at ucar.edu> wrote:
>>>>
>>>>> If you have a one-dimensional array (1D; eg: a 'time series') and a
>>>>> three-dimensional array (3D; eg: time series at multiple grid points), you
>>>>> *must* make the arrays 'conformant' for an array calculation
>>>>>
>>>>> You have:
>>>>> CoD1 = ((data_single(:) - data_subset(:,:,:))/(data_single(:) +
>>>>> data_subset(:,:,:)))^2
>>>>>
>>>>> You did not include a 'printVarSummary' of these variables. Assuming
>>>>> data_single(ntim) and data_subset(ntim,nlat,mlon) then you must replicate
>>>>> (aka, propogate) the 1D array to the 3D array size. In NCL, this is called
>>>>> 'array conformance' . Please see and carefully read:
>>>>>
>>>>> https://www.ncl.ucar.edu/Document/Functions/Built-in/conform.shtml
>>>>> https://www.ncl.ucar.edu/Document/Functions/Built-in/conform
>>>>> _dims.shtml
>>>>>
>>>>> ---
>>>>> DATA_SINGLE_3D = conform(data_subset, data_single, 0) ;
>>>>> (ntim,nlat,mlon)
>>>>> printVarSummary(DATA_SINGLE_3D) ; Look at data
>>>>>
>>>>> Do *not* use (:,:,:) in a computation... this is inefficient.
>>>>>
>>>>> CoD1 = ((DATA_SINGLE_3D - data_subset)/(DATA_SINGLE_3D+
>>>>> data_subset))^2
>>>>> printVarSummary(CoD1)
>>>>> printMinMax(CoD1, 0)
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Nov 7, 2017 at 11:15 AM, Kunal Bali <kunal.bali9 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Dear NCL user
>>>>>>
>>>>>> Suppose, I have 2 datasets
>>>>>> e.g.
>>>>>>
>>>>>> data1 = of single point lat & lon (e.g 28N, 72E) with time steps 365
>>>>>> (having filling values)
>>>>>> data2 = of grid box (24-32N, 68-76E) with time steps 365 (having
>>>>>> filling values)
>>>>>>
>>>>>> Now I want to calculate the CoD from one single point to 400km grid
>>>>>> box area and then lot the spatial map of the calculated product.
>>>>>>
>>>>>> Formula for CoD is GIVEN BELOW
>>>>>>
>>>>>>
>>>>>> So I calculated in NCL as
>>>>>>
>>>>>> CoD1 = ((data1 - data2)/(data1 + data2))^2
>>>>>> CoD_final = (sqrt(sum(CoD1)))/3
>>>>>>
>>>>>> please let me know is it the right way to do?
>>>>>>
>>>>>> I tried to plot the final product CoD_final with the attached script,
>>>>>> but error comes as
>>>>>>
>>>>>> fatal:Minus: Number of dimensions do not match, can't continue
>>>>>> fatal:["Execute.c":8578]:Execute: Error occurred at or near line 116
>>>>>> in file plot.ncl
>>>>>>
>>>>>>
>>>>>>
>>>>>> regards
>>>>>> Kunal Bali
>>>>>>
>>>>>>
>>>>>> _______________________________________________
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>>>>>> ncl-talk at ucar.edu
>>>>>> List instructions, subscriber options, unsubscribe:
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>>>>>>
>>>>>>
>>>>>
>>>>
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>>
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