[ncl-talk] "sum" and "avg" functions without ignoring missing values

[Rashed Mahmood]

Hi Arne,

Thanks for trying to answer the question, however, the things you mentioned
would add confusion and possibly wrong results.
Actually I know how to achieve what I want using a do loop. For example,
let us say we have variable a = (ntimes,nlevel,nlat,nlon) and we want to do
sum over time domain which can easily be done using: (dim_sum_n(a,0)), Now
the results would be sum over all non-missing values of
time1,time2,time2...timeN, which is correct.

But if I want to do sum ONLY when all of the values of
time1,time2,time3...timeN are non-missing then we can do this:

 dimz = dimsizes(a)
 b      = new(/dimz(1),dimz(2),dimz(3),float)
 b at _FillValue = a at _FillValue

  b(:,:,:) = 0.
  do n=0,dimz(0)-1
       b = b+a(n,:,:,:)
  end do

I just wanted to avoid the loop and use the "sum" function for efficiency.
I hope this clarifies the question a bit more.

Cheers,
Rashed














On Fri, Nov 24, 2017 at 3:01 AM, Arne Melsom <arne.melsom at met.no> wrote:

> Hi!
> Since 'music piano' replied, I thought I might chime in ;)
> I'm pretty sure that no option(s) to functions allow you to do what you
> want.
> So you'll need to write alternative functions yourself (perhaps not what
> you consider 'an easy way'...)
> You may use something like
>
> aDim = dimsizes(a)
> orgFill = a at _FillValue
> newFill = -min(abs(a)) - 1    ; make sure newFill is out of range and <0
> if (newFill .eq. orgFill) then  ; newFill must be different from orgFill
>   newFill = newFill - 1
> end if
> newVar = ndtooned(a)
> newVar at _FillValue = newFill
> indx = ind(ismissing(newVar))
> newVar(indx) = orgFill
> newa = onedtond(newVar,aDim)
>
> ...and, if you later want to restore:
> a = newa
> a at _FillValue = orgFill
>
> Hope this helps/clarifies!
> Best regards,
> Arne
>
>
> 2017-11-24 1:49 GMT+01:00 Rashed Mahmood <rashidcomsis at gmail.com>:
>
>> Hello all,
>> I am just wondering if there is an easy way to tell the "sum" and "avg"
>> functions NOT ignore the missing values. Below lines clarify my question
>> where I would like to see same values for c and d:
>>
>> ncl 0> a = (/(/-9.,2,-9./),(/1,-9.,2./)/)
>> ncl 1> a at _FillValue = -9.
>> ncl 2> c = (a(0,:)+a(1,:))
>> ncl 3> d = dim_sum_n(a,0)
>> ncl 4> print("  "+c+ " ... "+d)
>> (0)       -9 ... 1
>> (1)       -9 ... 2
>> (2)       -9 ... 2
>>
>> Thanks,
>> Rashed
>>
>>
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