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Re: Conditional Import

• To: mathgroup at smc.vnet.net
• Subject: [mg122393] Re: Conditional Import
• From: Leonid Shifrin <lshifr at gmail.com>
• Date: Thu, 27 Oct 2011 06:31:18 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <201110262139.RAA00083@smc.vnet.net>

As an alternative to writing your own import converter, which is a heavier
approach, you may try Read/ReadList or even BinaryRead/BinaryReadList. These
are fast (especially Binary..) lower-level functions which read from a
stream and might be enough for your purposes.

Regards,
Leonid


On Thu, Oct 27, 2011 at 1:39 AM, <sebastian.mansfeld at googlemail.com> wrote:

> Hi!
>
> I would like to import data from a very large text file. If I import all
> the data, Mathematica takes around 9 h to complete. Therefore I would like
> to import conditionally, that is for example only every 5th element. It
> would probably be best to do this using low level function. I have found a
> help topic on this (developing an import converter), however I can not get
> it to work. Specifically, I do not understand how to implement my own import
> converter, and how I can then use this to only import every 5th element of a
> file.
>
> Thank you!
>
>
>

• References:
  • Conditional Import
    • From: sebastian.mansfeld@googlemail.com