MathGroup Archive 2005

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

Search the Archive

Re: reducing the time of constructing a List


here is a simple and fast method:

lst = Table[ If[ dat[[i]] == 1, 1, 0], {i, Length[dat]}]

(Your timing should now be under 0.1 second)

Mariusz




>>> <marloo3 at mail15.com> 05/31/05 5:23 AM >>>
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: What is causing this error message?
  • Next by Date: Re: reducing the time of constructing a List
  • Previous by thread: Re: reducing the time of constructing a List
  • Next by thread: Re: reducing the time of constructing a List