Re: Reading Fortran data files

[Mark Verschell <markverschell@xxxxxxxxxxxxxx>]

Oh, tough questions....

The basic problem is that ForTran is so very good at creating whatever output you want. I think however that both can be solved, one easily and one with a little trickery.

For WeiQiang:
With direct access output you are missing the 4 bytes that are at the beginning and end of each record in a typical ForTran data file (this is the record length - not needed in direct access when all records are SUPPOSED to be the same length), that is why the /format=unformatted won't work for you. Try instead:
set data/format=stream/columns=3240/var=map1 data.dat

For Aiguo:
Yours is a little tougher because (if I remember correctly) what you have in each record would be:
4 bytes of record length (9720*4=38880)
12960 bytes of map1
12960 bytes of map2
12960 bytes of map3
4 bytes of record length (9720*4=38880)
There isn't a super clean way to read these (again, if I remember correctly). The only thing I can think to try is to "fool" ferret and access map1-3 (or amp, pha, and avg) as a single variable with depth. Try something like (CHANGES IN CAPITALS):
def axis/x=180W:180E/npoint=72/unit="degrees_east" lon
def axis/y=90S:90N/npoint=45/unit="degrees_north" lat
DEF AXIS/Z=1:3:1 NVAR                                                                            ! CHANGE
def axis/t=1:5:1 time
def grid/x=lon/y=lat/Z=NVAR/t=time g5x4                                                ! CHANGE
file/format=unformatted/var=MAPS/col=9720/grid=g5x4 data.dat      ! CHANGE
!
LET AMP=MAPS[Z=1]                                                                                 ! CHANGE
LET PHA=MAPS[Z=2]                                                                                 ! CHANGE
LET AVG=MAPS[Z=3]                                                                                 ! CHANGE
set var/bad=-99999. amp
set var/bad=-99999. pha

Good Luck to you both! Mark

On Thursday, July 19, 2001, at 10:32 PM, weiq wrote:

> Hello, 
> Another similiar question in the following:
> parameter(mi=72,mj=45,msea=5)
> real map1(mi,mj)
>
> open(1,form='unformatted',file='data.dat',access='direct',recl=mi*mj)
>
> do is=1,msea
> write(1,rel=is)  map1
> enddo
>
> How can read this data.dat using ferret? I try it sometimes, but i failed.
> By the way, I can read the above data.dat using Matlab, using fread(fp1,[72,45],'float32'). But I must using ferret to read it for graphic output.
>
>
> ---------------------------------------------
> Wang WeiQiang
> LED, South China Sea Institute of Oceanology
> Chinese Academy of Sciences
> 164 West Xingang Rd., Guangzhou 510301
> P. R. China
> --------------------------------------------   
>
>
> ----- Original Message ----- 
> From: "Aiguo Dai" <adai@ucar.edu>
> To: <ferret_users@ferret.wrc.noaa.gov>
> Sent: Friday, July 20, 2001 2:08 AM
> Subject: Reading Fortran data files
>
>
> > Try this again:
> > > Hello,
> > >
> > > I was trying to read Fortran 77 files similar to the following one:
> > >
> > > parameter(mi=72,mj=45,msea=5)
> > > real map1(mi,mj),map2(mi,mj),map3(mi,mj)
> > >
> > > open(1,form='unformatted',file='data.dat')
> > >
> > > do is=1,msea
> > > write(1)map1,map2,map3
> > > enddo
> > >
> > > using Ferret scripts:
> > >
> > > def axis/x=180W:180E/npoint=72/unit="degrees_east" lon
> > > def axis/y=90S:90N/npoint=45/unit="degrees_north" lat
> > > def axis/t=1:5:1 time
> > > def grid/x=lon/y=lat/t=time g5x4
> > > file/format=unformatted/var=amp,pha,avg/col=9720/grid=g5x4 data.dat
> > > !
> > > set var/bad=-99999. amp
> > > set var/bad=-99999. pha
> > >
> > > However, the maps for amp[l=1], ..., amp[l=5], and pha are incorrect.
> > >
> > > Any suggestions would be appreciated for reading this types of data
> > > files (also for cases with only map1 and map2 written). Thanks lot.
> > >
> > > -Aiguo Dai, NCAR, Boulder, CO