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Re: Compress timing with different data types

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97735] Re: Compress timing with different data types
  • From: mark mcclure <mcmcclur at unca.edu>
  • Date: Fri, 20 Mar 2009 02:38:53 -0500 (EST)
  • References: <gpsr4o$mh9$1@smc.vnet.net>

On Mar 19, 3:10 am, Yves Klett <yves.kl... at googlemail.com> wrote:
> I noticed that the speed of Compress is very much dependent on
> the type of data that is compressed:
> ...
> compressing an expression only containing lists and numbers is about
> 60 times faster than compressing an expression containing Line
> statements. And the difference gets worse the larger the expression
> becomes...
>
> Does anyone have experience and/or a workaround with that
> behaviour (6.03 & 7.01 on WinXP)?

Running your code in both V6.0.3 and V7.0.1 on my Mac laptop, I get
speed ratios of more like 6 or 7, rather than 60.  Of course, I wouldn't
expect Compress to accomplish anything with an array of random
numbers, while an expression containing many copies of a Line
primitve would be compressed a lot.  Perhaps this has something to
do with it.

Incidentally, there's no reason to map Line onto data.  That is
Line[data] is perfectly valid and renders faster than Line /@ data.

Mark McClure



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