Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2005
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2005

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

Search the Archive

Re: reducing the time of constructing a List

  • To: mathgroup at smc.vnet.net
  • Subject: [mg57556] Re: reducing the time of constructing a List
  • From: dh <dh at metrohm.ch>
  • Date: Wed, 1 Jun 2005 06:01:42 -0400 (EDT)
  • References: <d7haeo$3pa$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,
try replacing every elemnt different from 1 by zero:

dat /. x_Integer -> 0 /; x != 1

sincerely, Daniel

marloo3 at mail15.com wrote:
> please, what is the best way to reduce the timing of the following lines, the 
> source of data is:
> dat = Table[Random[Integer, {0, 10}], {100000}];
> and the purpose is to construct the List lst in the following way:
> For[i = 1, i <= 100000,
>       If [dat[[i]] == 1,
>         lst = Join[lst, {1}], lst = Join[lst, {0}]]; i++]; // Timing
> 
> Out[]= {226.07 Second, Null}
> on the P4 celeron 2 Ghz , memory 382 MB ram
> thanks
> 


  • Prev by Date: Re: reducing the time of constructing a List
  • Next by Date: Re: What is causing this error message?
  • Previous by thread: Re: reducing the time of constructing a List
  • Next by thread: Re: reducing the time of constructing a List