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Re: reducing the time of constructing a List


lst = dat /. x_Integer /; x â?  1 -> 0;

or

lst = dat /. {1 -> 1, x_Integer -> 0};

or

lst = Boole /@ Thread[dat == 1];

Bobby

On Tue, 31 May 2005 05:00:08 -0400 (EDT), <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
>
>
>
>



-- 
DrBob at bigfoot.com


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