Re: Reading from process pipes in IDL?

[Craig Markwardt <craigmnet(at)cow.physics.wisc.edu>]

landsman@mpb.gsfc.nasa.gov writes:
> In V5.3, the /COMPRESS keyword was introduced to OPENR, which allows you
> to directly access gzip'ed files in an OS-independent way.   I've been
> quite happy with this feature -- you can read compressed files almost
> completely transparently.    One thing to watch out for, is that
> although POINT_LUN works on compressed files, it is much slower than on
> regular files, since IDL always has to reset to the beginning on each
> POINT_LUN call for compresed files.

I agree that this IDL v5.3 feature sounds pretty cool.  I wonder when
we'll get it here...  The seek slowdown you mentioned does not occur
in my seekable pipes library.  The seek is lazy, which means that no
data is uncompressed until it actually needs to be read.  You pay the
price however, by needing a temporary storage area to hold the
uncompressed data.

Craig

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Craig B. Markwardt, Ph.D.         EMAIL:    craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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