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