Hi Roy: I had a similar problem earlier this year. I wanted to open a
netCDF 3 file and read from it using the netCDF library when the file
was presented to me in memory instead of as a disk file.
I spent some time examining the netCDF library source and talking to
UNIDATA folks about this and determined that the library was too hard to
change. The interface depended upon passing in a file name and it would
be too hard to modify it to add an 'ncopen' that took a pointer to
memory instead.
What I ended up doing was writing a reader from scratch in perl (since
this application was in perl using the PDL::NetCDF interface) that reads
the raw netCDF3 binary format.
This has proved to be a good lightweight solution for us, but it does
restrict us to netCDF 3.
I'd be happy to share my perl netCDF 3 reader library if you are interested.
Incidentally, as a result of this experience, I came away with an
appreciation for the elegance and good design of the netCDF 3 binary
format and a suspicion of the netCDF 4 format as being too complex and
having too much library overhead.
Regards,
Doug
On 11/19/14 18:41, Roy Mendelssohn - NOAA Federal wrote:
Hi All:
Netcdf now has the option of creating or reading a file entirely in memory, a
nice option to have. I am wondering if there is any way to do sort of the
inverse. Some web libraries allow for a pure binary download of a file into
memory, so what I have sitting there is essentially a binary image of the
netcdf file. Is there any way to open that image without writing to disk?
As an example, the R httr library allows this. I can for example download to memory a netcdf
file from ERDDAP, and if I then do a binary save in httr and then read it back in using the
ncdf4 package, it all works great. But it would be even better if I could skip the extra
steps, and “open” the image in ncdf4 directly (ncdf4 btw can do whatever the
netcdf libraries can do, so it is a question of the base libraries).
Thanks,
-Roy
**********************
"The contents of this message do not reflect any position of the U.S. Government or
NOAA."
**********************
Roy Mendelssohn
Supervisory Operations Research Analyst
NOAA/NMFS
Environmental Research Division
Southwest Fisheries Science Center
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e-mail: Roy.Mendelssohn@xxxxxxxx www: http://www.pfeg.noaa.gov/
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