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MathGroup Archive 2000

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Import[] command 100 times slower than ReadList [] ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg23439] Import[] command 100 times slower than ReadList [] ?
  • From: "Krautschik, Chris G" <krautschikc at intel.co.jp>
  • Date: Wed, 10 May 2000 02:32:21 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

Hi Mathgroup,

Manny thanks to all of you who helped me get my previous data matrix problem
solved ( Allan Hayes, Bob Hanlon, and Mark Harder).

I have been using the Import command to import various 2-D data matrices.
For a 513x122 data matrix text file I use the following command:

xyData=Import["xyFile.txt","Table"]

This task takes 117 seconds to complete (as timed by Timing[]).

When I use ReadList:

inFile = OpenRead["xyFile.txt"];
xyData = ReadList[ inFile, Number, RecordLists -> True];
Close[inFile];

This task only takes 1.26 seconds.

Why the huge performance difference?  I would prefer to use the Import
command since it is so easy to use but find it too slow for my uses.

thanks,
Chris



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