Hi Doug:
Thanks for the comments. I would be interested on seeing the perl code, just to
see how complicated it is to do this (though I don’t really know perl). Fro my
purposes. since this is something we will be distributing, we want to keep
what we do to code that is “native” to the program, in this case R.
-Roy
On Nov 20, 2014, at 8:48 AM, Doug Hunt <dhunt@xxxxxxxx> wrote:
> 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
>> ***Note new address and phone***
>> 110 Shaffer Road
>> Santa Cruz, CA 95060
>> Phone: (831)-420-3666
>> Fax: (831) 420-3980
>> e-mail: Roy.Mendelssohn@xxxxxxxx www: http://www.pfeg.noaa.gov/
>>
>> "Old age and treachery will overcome youth and skill."
>> "From those who have been given much, much will be expected"
>> "the arc of the moral universe is long, but it bends toward justice" -MLK Jr.
>>
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>
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**********************
"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
***Note new address and phone***
110 Shaffer Road
Santa Cruz, CA 95060
Phone: (831)-420-3666
Fax: (831) 420-3980
e-mail: Roy.Mendelssohn@xxxxxxxx www: http://www.pfeg.noaa.gov/
"Old age and treachery will overcome youth and skill."
"From those who have been given much, much will be expected"
"the arc of the moral universe is long, but it bends toward justice" -MLK Jr.
