[ncl-talk] wrf_user_getvar - select time period

[Dennis Shea]

Unfortunately,  that 'custom script' has disappeared.

[1] If the variable is on the file, then you can read it directly. If there
are (say) 25 time steps but you only want 5 specified times,then:

     it = ispan(7,11,1)
     u = f->U(it,:,:,:)

     even

    it = (/3,7,8,9,21/)
    u = f->U(it,:,:,:)

[2] I **speculate**  that what was done was something like the following

undef("wrf_user_getvar_time_subset")
function wrf_user_getvar_time_subset(f, varName[1]:string, it[*]:integer)
local nit, dims, rank, n, x
begin
   nit     = dimsizes(it)
   dims = getfilevardimsizes(f,varName)
   rank  = dimsizes(dims)
   if (rank.eq.3) then
       x = new((/nit,dims(1),dims(2)/),"float")
       do n=0,nit-1
          x(n,:,:) = wrf_user_getvar(f,varName,it(n))
       end do
   elseif (rank.eq.4) then
       x = new((/nit,dims(1),dims(2),dims(3)/),"float")
       do n=0,nit-1
          x(n,:,:,:) = wrf_user_getvar(f, varName, it(n))
       end do
   end if

   x!0 = "Time"
   return(x)
end

;------------------
   dirwrf = "./"
   filwrf = "wrfout_d01_000000.nc"
   pthwrf = dirwrf+filwrf
   fwrf   = addfile(pthwrf,"r")

   it     = (/3,7,8,9,21/)
   varName= "U"

   u      =  wrf_user_getvar_time_subset(fwrf, varName, it)
   printVarSummary(u)


On Mon, Mar 16, 2020 at 9:47 PM Dong via ncl-talk <ncl-talk at ucar.edu> wrote:

> Hi,
> I'm using NCL 6.5 in Ununtu and have a question.
>
> I found that  "wrf_user_getvar"  only can get a specific time or all
> times but I want to retrieve a subset of times.
>
> Fortunately ,I find a solution in your website
> http://www.ncl.ucar.edu/Support/talk_archives/2009/2720.html
>
> The website said there are two ways I can do this. My data is so big that
> I can't retrieve all times （the .ncl script will be killed without any error
> message ）and I want to use the second way :
>
> load "./wrfslp.ncl"
>
> and then call with:
>
> times = ispan(0,10,1)
>
> slp = wrf_user_get_slp(z,times)
> However, I can't load "./wrfslp.ncl" or download you attachment from your
> talk_archives: http://www.ncl.u
> car.edu/Support/talk_archives/2009/2720.html
>
> Any help greatly appreciated.
>
> Thanks,
> Dong
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