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MathGroup Archive 2008

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BinaryReadList with Mixed Types

  • To: mathgroup at smc.vnet.net
  • Subject: [mg92965] BinaryReadList with Mixed Types
  • From: Raffy <raffy at mac.com>
  • Date: Tue, 21 Oct 2008 06:23:30 -0400 (EDT)

When BinaryReadList is used with mixed types like
{"UnsignedInteger32", "Real32"}, the speed at which it imports is
incredibly slow.

count = 10000;

file = OpenWrite["Slow.dat", BinaryFormat -> True];
BinaryWrite[file,
  Transpose@{RandomInteger[{0, 1}, count],
    RandomReal[{0, 1}, count]}, {"UnsignedInteger32", "Real32"}];
Close[file];

file = OpenWrite["Fast.dat", BinaryFormat -> True];
BinaryWrite[file,
  RandomReal[{0, 1}, {count, 2}], {"Real32", "Real32"}];
Close[file];

BinaryReadList["Slow.dat", {"UnsignedInteger32", "Real32"}]; // Timing
--- takes about 0.5 sec
BinaryReadList["Fast.dat", {"Real32", "Real32"}]; // Timing --- a few
ms at most

Is there anyway I can fix this performance?  The current speed is
completely unacceptable.

Thank you.


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