[ncl-talk] handling binary data with direct access

[Arijeet Dutta]

Hi, thanks for the corrections. The fortran reading and writing part seems
logically correct but it's showing "Fortran runtime error: Non-existing
record number"!

On Fri, Oct 20, 2017 at 10:12 PM, Dennis Shea <shea at ucar.edu> wrote:

> If you are "new to NCL", please read the NCL User Guide created by DKRZ.
> There are many examples.
>
> https://www.ncl.ucar.edu/Document/Manuals/NCL_User_Guide/
>
> ==============
> BinCreate.ncl (modified bincreate.ncl)
>
> f1 = addfile("uwnd.850.1951.nc","r")
> uwnd = f1->uwnd
> dimu  = dimsizes(uwnd)
> ntim   = dimu(0)
>
>    do i = 0=ntim-1    ; each 'i' (time) is a record number
>      fbindirwrite ("1951.bin",uwnd(i,:,:))  ; each time (record number)
> has lat*lon pts
>     end do
>
> ==================
> Your binread.f95 is odd (?not correct?).
>
> (a) You are opening units 11 and 12 but not reading either file (unit).
> Why are they there?
>
> (b) Where is 'uwnd' created? ***Where is the 'time' (record) dimension?***
>
> (c) Further, it is *writing* (nor *reading* as the file name would imply)
> one grid point value at each iteration.
>
> To read what 'BinCreate.ncl' is doing you would need something like:
>
> implicit none
> integer::time,lon,lat,i,j,k,nu,nr
> parameter (time=730)
> parameter (lat=25)
> parameter (lon=144)
> real::uwnd(lat,lon)
>
> open(11,file="1950.bin",form="unformatted",access="direct",recl=4*lat*lon)
> open(21,file="1951.bin",form="unformatted",access="direct",recl=4*lat*lon)
> open(31,file="50_51.bin",form="unformatted",access="direct",
> status="replace",recl=4*lat*lon)
>
>
>      nr = 0
>      do nu=11,21,10
>         do i = 1,time
>            read(nu,rec=i) uwnd    ! read all lat*lon
>            nr = nr+1
>            write(31,rec=nr) uwnd  ! write all lat*lon
>
>         end do
>      end do
>
> close(31)
> close(21)
> close(11)
>
> end
>
>
> ====================
>
> Good luck
>
>
> On Fri, Oct 20, 2017 at 7:05 AM, Arijeet Dutta <arijeet.uoh at gmail.com>
> wrote:
>
>> Hi, I am aware of addfiles() and I am able to merge nc files, that's not
>> the issue; I am just playing around with fbindirread and fbindirwrite and
>> make sense of them. Please have a look when you get time. Thanks
>>
>> Cheers
>> Arijeet
>>
>> On Fri, Oct 20, 2017 at 6:17 PM, Rick Brownrigg <brownrig at ucar.edu>
>> wrote:
>>
>>> I've not looked at the scripts just yet, but if all you are trying to do
>>> is to merge several NetCDF files, you might want to look at the addfiles()
>>> command:
>>>
>>> http://ncl.ucar.edu/Document/Functions/Built-in/addfiles.shtml
>>>
>>> This potentially save you some trouble.
>>>
>>> On Fri, Oct 20, 2017 at 6:17 AM, Arijeet Dutta <arijeet.uoh at gmail.com>
>>> wrote:
>>>
>>>> Hi all, I am new to NCL. I had u-wind daily data at 850hPa as netcdf
>>>> files. To get into how binary file works I converted the nc file into .bin
>>>> using fbindirwrite and then used fortran to read and merge two such files
>>>> and then tried to read the merged bin file in NCL with fbindirread I am
>>>> having unrealistic values for u-wind. Please see the attached scripts I
>>>> wrote and let me know if you can make out anything
>>>>
>>>> Cheers
>>>> Arijeet
>>>>
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>>
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