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Re: Writing compressed HDF5 files with IDL [message #69846]

Wed, 17 February 2010 04:09

Maarten[1]
Messages: 176
Registered: November 2005

Senior Member

On Feb 16, 4:16 pm, Carsten Lechte <c...@toppoint.de> wrote:
> Thanks for your reply.
>
> Maarten wrote:
>> h5repack --native --latest --filter=GZIP=6 file.h5 file-out.h5
>
> Yes, that's what I am doing at the moment, but it is annoying to
> write gigabytes of data, then compress it, then delete it.

Have a look at the h5d_create function. I just checked for IDL version
6.4, and it has a gzip named parameter. Using this (and other
parameters will create compressed datasets.

Maarten

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Re: Writing compressed HDF5 files with IDL [message #69850 is a reply to message #69846]

Tue, 16 February 2010 07:16

Carsten Lechte
Messages: 124
Registered: August 2006

Senior Member

Thanks for your reply.

Maarten wrote:
> h5repack --native --latest --filter=GZIP=6 file.h5 file-out.h5

Yes, that's what I am doing at the moment, but it is annoying to
write gigabytes of data, then compress it, then delete it.

chl

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Re: Writing compressed HDF5 files with IDL [message #69851 is a reply to message #69850]

Tue, 16 February 2010 07:08

Maarten[1]
Messages: 176
Registered: November 2005

Senior Member

On Feb 16, 2:50 pm, Carsten Lechte <c...@toppoint.de> wrote:
> Has anyone managed to write (gzip) compressed HDF5 files with IDL?
> My guess is that it is not possible with IDL 6.4.
>
> The help for the high-level function H5_CREATE does not mention
> compression, and the low-level functions for the H5P_* interface
> are noticable only for their absence. The H5P_* functions are
> necessary for setting the compression options.

HDF5 support was introduced quite slowly, it took RSI/ITT a few
iterations to get it right (well, complete). Your best bet is to
compress after creation.

In the shell (unix, right?) you can spawn the following. h5repack is
part of hte HDF5 library distribution. Be sure to read the help of the
tool; note that --latest may prevent IDL from reading the file (if you
have HDF5 1.8 installed).

h5repack --native --latest --filter=GZIP=6 file.h5 file-out.h5

Best,

Maarten.

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Re: Writing compressed HDF5 files with IDL [message #69967 is a reply to message #69846]

Fri, 19 February 2010 12:33

Carsten Lechte
Messages: 124
Registered: August 2006

Senior Member

Maarten wrote:
> Have a look at the h5d_create function. I just checked for IDL version [...]

Good find! I will try that approach.

chl

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