MathGroup Archive: February 2008 [00081]

[Date Index] [Thread Index] [Author Index]

Re: Efficient way of reading matrices

To: mathgroup at smc.vnet.net
Subject: [mg85291] Re: Efficient way of reading matrices
From: "Szabolcs HorvÃt" <szhorvat at gmail.com>
Date: Tue, 5 Feb 2008 06:09:22 -0500 (EST)
References: <fo3gad$b3p$1@smc.vnet.net>

In Feb 5, 2008 7:22 AM,  <m.r at inbox.ru> wrote:
>
> Hi Szabolcs,
>
> maybe you can read and pack your matrix row by row:
>
> WriteString["/zzz", Sequence @@ Riffle[#, " "], "\n"]& /@
>   RandomInteger[{-1000, 1000}, {200, 250000}]
> Close["/zzz"]
>  (*a test file*)
>
> (m = Developer`ToPackedArray@ Read["/zzz",
>   Array[Number&, 250000]]& /@ Range[200];) // Timing
> Close["/zzz"]
>

Thanks you Maxim Rytin,

Good and useful suggestion, as always. :-)  I have already written a
MathLink matrix reader program to do the work, but your program
(though slower) uses even less memory as it never needs to store two
copies of the complete matrix in memory.

Szabolcs HorvÃ¡t

Prev by Date: Re: pattern matching against the Dt function?

Next by Date: Re: Accessing the contents of the clipboard

Previous by thread: Re: Efficient way of reading matrices

Next by thread: Re: Efficient way of reading matrices