[ncl-talk] Removing some data from NetCDF file for a specific date

[Dennis Shea]

As noted by DaveA, the question is ambiguous.
The following will set the times times by the user. to _FillValue
Sine _FillValue are not used in any computation, this is similar to
'removing' the times from the variable.

      ymd_exclude = (/19830131, 19850202, 19890610/) ; times to remove

   diri = "./"      ; input directory
      fili = "model.nc"
      f = *addfile*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/addfile.shtml>(diri+fili,
"r")

      x = f->X
      printVarSummary(x)

     ymd  = *cd_calendar*
<http://www.ncl.ucar.edu/Document/Functions/Built-in/cd_calendar.shtml>(x&time,
-2)         ; yyyymmdd ... all ymd in file
     nt_exclude       = *get1Dindex_Exclude*
<http://www.ncl.ucar.edu/Document/Functions/Contributed/get1Dindex_Exclude.shtml>(ymd,
ymd_exclude)
     x(nt_exclude,...) = x at _FillValue          ; set all remove time
to _FillValue

                                                                 ;
size of 'x' unchanged

======

Alternatively, actually remove the 'ymd_exclude' times from the variable.

The size of the array wil change.


     nt_collapse  = *get1Dindex_Collapse*
<http://www.ncl.ucar.edu/Document/Functions/Contributed/get1Dindex_Collapse.shtml>(ymd,
ymd_exclude)
     x *:=* x(nt_collapse,...)                          ; note use of
'reassignment' operator [ *:=* ]
     printVarSummary(x)                            ; note change of size
=======

Other useful index utility functions

*get1Dindex* <http://www.ncl.ucar.edu/Document/Functions/Contributed/get1Dindex.shtml>,
*ind* <http://www.ncl.ucar.edu/Document/Functions/Built-in/ind.shtml>


On Fri, Jan 17, 2020 at 4:02 AM Setareh Rahimi via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Dear Dave,
> I have only my NCL script to plot some variables from model results. As I
> mentioned before in those model results there are some specific dates that
> I need to remove. So I am seeking a way t do so, and I did not write any
> application program in NCL to remove them.
> Best wishes,
>
> On Fri, Jan 17, 2020 at 2:31 AM Dave Allured - NOAA Affiliate <
> dave.allured at noaa.gov> wrote:
>
>> Please keep replies on the mailing list.  I assumed that you were writing
>> your own application program in NCL.  Is this correct, or do you just want
>> to make reduced files?
>>
>>
>> On Thu, Jan 16, 2020 at 5:38 AM Setareh Rahimi <setareh.rahimi at gmail.com>
>> wrote:
>>
>>> Dear Dave,
>>> Many thanks for your email, and apologize for the slow reply. Well, I
>>> think method 2 should be fine. However, which application program do you
>>> suggest?
>>> Best wishes,
>>>
>>> On Tue, Jan 7, 2020 at 10:58 PM Dave Allured - NOAA Affiliate <
>>> dave.allured at noaa.gov> wrote:
>>>
>>>> I can think of at least three ways to do this.
>>>>
>>>> 1.  Write a program to copy grids from a model file into a new file,
>>>> but skip selected dates.
>>>> 2.  In your application program, remove the selected dates from a copy
>>>> of the model data in program memory.
>>>> 3.  In your application program, read in only the dates wanted, and
>>>> skip the dates to be removed.
>>>>
>>>> I recommend methods 2 or 3 because they are fast and efficient, and
>>>> need less programming than the first method.  2 and 3 require the ability
>>>> to make changes to your application program.  Which method fits your needs?
>>>>
>>>>
>>>> On Tue, Jan 7, 2020 at 1:23 AM Setareh Rahimi via ncl-talk <
>>>> ncl-talk at ucar.edu> wrote:
>>>>
>>>>>
>>>>> Dear all,
>>>>>
>>>>> I have some model outputs in the NetCDF format. I need to remove the
>>>>> results from the files for some specific dates (like 2008/02/04). So would
>>>>> you please kindly advise me how can I do so?
>>>>> Many thanks in advance,
>>>>> Best wishes,
>>>>> --
>>>>> S.Rahimi
>>>>>
>>>>
>
> --
> S.Rahimi
>
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