| Re: How to check if a file is indeed a NetCDF file? [message #15032] |
Mon, 19 April 1999 00:00 |
Liam Gumley
Messages: 473
Registered: November 1994
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Senior Member |
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Paul van Delst wrote:
> In trying to read NetCDF data files in IDL, I've discovered that the
> NCDF_OPEN crashes on me if the file I ask it to open is not a nCDF file.
> It crashes somewhat gracefully in that it tells me that NCDF_OPEN
> couldn't open the file and the error # is 19. Does anyone out there know
> how to use the IDL NCDF library to determine whether or not a file is in
> NetCDF format? The fact that the most obvious solution (i.e. NCDF_OPEN
> *returns* an error # rather than falling in a heap) doesn't work like I
> would expect doesn't make me too hopeful.
How about this (styled along the lines of HDF_ISHDF)?
FUNCTION NCDF_ISNCDF, FILENAME
;- Set return values
false = 0B
true = 1B
;- Establish error handler
catch, error_status
if error_status ne 0 then begin
catch, /cancel
return, false
endif
;- Try opening the file
cdfid = ncdf_open( filename )
;- If we get this far, open must have worked
ncdf_close, cdfid
catch, /cancel
return, true
END
Then it's just a matter of:
if not ncdf_isncdf( filename ) then begin
help, filename
message, 'FILENAME is not in NetCDF format'
endif
cdfid = ncdf_open( filename )
Cheers,
Liam.
---
Liam E. Gumley
Space Science and Engineering Center, UW-Madison
http://cimss.ssec.wisc.edu/~gumley
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| Re: How to check if a file is indeed a NetCDF file? [message #15033 is a reply to message #15032] |
Mon, 19 April 1999 00:00  |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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Paul van Delst wrote:
> Hello,
>
> In trying to read NetCDF data files in IDL, I've discovered that the
> NCDF_OPEN crashes on me if the file I ask it to open is not a nCDF file.
> It crashes somewhat gracefully in that it tells me that NCDF_OPEN
> couldn't open the file and the error # is 19. Does anyone out there know
> how to use the IDL NCDF library to determine whether or not a file is in
> NetCDF format? The fact that the most obvious solution (i.e. NCDF_OPEN
> *returns* an error # rather than falling in a heap) doesn't work like I
> would expect doesn't make me too hopeful.
>
> Any info appreciated.
>
> paulv
>
> --
> Paul van Delst
> Space Science and Engineering Center | Ph/Fax: (608) 265-5357, 262-5974
> University of Wisconsin-Madison | Email: paul.vandelst@ssec.wisc.edu
> 1225 W. Dayton St., Madison WI 53706 | Web: http://airs2.ssec.wisc.edu/~paulv
read the first 3 Bytes
You will found 'CDF' if it's a netCDF File.
R.Bauer
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